Which part of Bluetooth do you dislike? These days it’s more like a family of standards.

This is the problem. Just because two devices both feature the Bluetooth logo doesn't actually mean they'll play nicely together.

How about not being able to rename devices? And vendors choosing the most ridiculous device names?

I bought my kids two identical headphones. How do I make sure each headphone is connected to the right device? It's infuriating.

(It's possible to change the name of all Apple bluetooth devices, but why other vendors don't copy this feature is something I just don't understand)

I believe the commenter has no idea and is just repeating a common phrase.

To take an example, BLE is really quite good, and works reliably.

It's slow. Transfering videos from my iPhone to my MacBook happens very fast, sending a video from a friends Android phone to my Thinkpad takes forever.

Over Bluetooth? Yeah, that would be slow. The Apple devices are almost certainly spinning up a WiFi connection to actually move the data. I imagine that both the Android phone and the ThinkPad can be taught how to do that, but it doesn't surprise me that it didn't just work out of the box.