I like the conceptual separation. I like alt-tabbing to "Slack" not "Chrome". It also doesn't have any of the header bar so the electron app has more UX control, including access to OS level window menu options. Also it can do things that you can't do inside the browser. E.g., I've seen electron apps that come with other background processes. I also think it performs better in terms of versioning/caching resources. So an electron app could be just a web-site, but they often are much more.
That's true but some of that could already be implemented in browsers itself. E.g. web page could request to be in a separate window with different icon and ask for OS-wide api permissions. Now we have to run several fully-featured browser (Elecron) instances, not sharing system libraries, under different versions. This reminds me "write once, run everywhere" Java with bundled binary JREs because of incompatibilities between vendors... But there is some progress - for example IBKR TWS client can't play sounds as it was linked with an old libavformat.so which I no longer have in the system. Browsers have most of libs statically linked.
