Performance. Alex Russell, formerly of Google and now the product owner of Microsoft Edge loves to rant about it. His latest rant is how Edge has significantly improved the performance of some of its UI features by moving off React [0].
As I read this thread, it's not like "React was the issue, let's move to [other framework]", it's more like moving closer to the plattform brought a performance boost.
And that's something I would totally agree. Moving from WebUI to native UIs would even be more performant, and if one would care that much about performance (as said in the thread), one would probably not look at WebUI/Electron/Browser at all and prefer native apps.
The options we have today are not the options we had at the time Facebook introduced React. React solved tons of browser shortcomings that are finally being fixed in the actual browser.
[0] https://blogs.windows.com/msedgedev/2024/05/28/an-even-faste...