Switching from a large, complex tool that includes a learning curve is expensive. You set a high bar for switching from Eclipse because you are used to it, paid a learning price and are productive in it. And you are right. But that also means that picking such a tool from a multitude of options should be done after careful consideration, which is exactly what using smaller tools provides.
On a somewhat related note, I want my professional software to only provide a (great) speedup of development. I want them to only do what I could do without them (even if it takes a week instead of a minute). This means I can often look at things that fail to work and understand what is failing. This is also helped by new engineers starting with smaller tools and building up to integrated, distributed tools only after knowing how individual elements work and can be connected. Integrating with a (good) big tool is then not a fight as it brings a "wow" moment -- "instead of doing all this by hand I can do it with a few mouseclicks!". My 2c.
[Talking from the perspective of Eclipse, because it's the only IDE I invested my time in]
In this case, it's not. Eclipse put Integrated into IDE, but doesn't subtract transparency in the process. You can see what it does, tweak every step meticulously if you want, and return to defaults with one click, if you prefer.
What this transparency brings is mental flexibility and understanding. Do I want or need to switch? I'm doing the same thing in Vim or KATE of BBEdit in 15 minutes. Maybe I stumble with a couple of shortcuts, but that's not a problem.
The funny thing is I see the compiler command every time I press build, so it's burned in my memory after a day. While I can read valgrind outputs and understand what it says, Eclipse highlights the lines automatically, so I'm faster. While I can gnuplot performance graphs, Eclipse auto-builds them so they are on my desktop after a 10 hour torture run.
In my case, Eclipse enables me to carry a whole toolbox and more in a single folder, yet all the tools it uses and what it does is so transparent that I can switch away on an instant if I don't get my installation with me, or I'm connecting to a server in a datacenter far, far away.
I don't like to be blindsided by my tools. I like blinkenligths in a way, and Eclipse gives me these blinkenlights while being highly automatic.
So while I understand your case, it doesn't apply to Eclipse, at least, because it's not a strangler, but a great enabler and HUD in my experience.
For the time investing part, I don't grind. I get a tool, and start using it, and when it becomes limiting, I start poking it and learn what feature solves that problem at hand. By that way, I learn the tool as I go, and if the tool can't expand to my needs at some point, it fades away from use gracefully. I don't do "stop, drop, roll" thing while changing tools, so I can't paint a timeline about when I picked a tool and dropped another.
I think the big drawback to eclipse is it's a beast to get setup correctly before it performs well. It's built to support everything, but really does a pretty poor job out of the box.
I primarily do Java development. I started with eclipse, fell away because at the time it had pretty awful maven support. Moved over to Netbeans which has pretty good maven and java support, but went through a somewhat "unsupported" period of time and ultimately I moved over to intellij.
Intellij has been a joy to work with in Java code bases because everything just works and the smart features are actually worth it. Intellij can do pretty major refactors that both netbeans and eclipse can't think of. Further, it has really good code improvement suggestions that neither eclipse nor netbeans had. I can also simply check out any code base and tell intellij to open it and be up and running immediately.
A yellow line in intellij is almost certainly something you can right click on and hit "make better" and you'll have better and easier to understand code as a result.
All that said, you sound like you are working with a C/C++ environment. I've not done a lot with Intellijs clion so I couldn't tell you how comparable it is. It wouldn't shock me to learn eclipse is better as intellij is really well built for dynamic languages, maybe not so much for statically compiled languages.
I have never written Java projects so big that used Maven in any capacity. Instead, I'm using it with C/C++ as you guessed and Python. Also XML, JS and other supported parts of the projects I write go through Eclipse if the projects themselves are beyond a certain size.
For C/C++, Eclipse has a "so-called" indexer, which indexes the whole project, does static analysis on the fly, provides great auto-complete and warns you about gotchas. Since it can read the whole project, it has a better view than a C++ LSP, and it works reasonably fast and provides great detail.
Also, Eclipse has "Linux Tools Integration", which is also a boon for C++ development on Linux.
All in all, it helped me to build a materials simulation code without any memory leaks and with great performance insights, so I can't complain. Plus, I love build and launch profiles of that thing.
Switching from a large, complex tool that includes a learning curve is expensive. You set a high bar for switching from Eclipse because you are used to it, paid a learning price and are productive in it. And you are right. But that also means that picking such a tool from a multitude of options should be done after careful consideration, which is exactly what using smaller tools provides.
On a somewhat related note, I want my professional software to only provide a (great) speedup of development. I want them to only do what I could do without them (even if it takes a week instead of a minute). This means I can often look at things that fail to work and understand what is failing. This is also helped by new engineers starting with smaller tools and building up to integrated, distributed tools only after knowing how individual elements work and can be connected. Integrating with a (good) big tool is then not a fight as it brings a "wow" moment -- "instead of doing all this by hand I can do it with a few mouseclicks!". My 2c.