None of those have required me to install a particular extension..
Of course thats not to deny your experience!
The only time profiles ever come into it, for me, is using web driver, playwright, or whatever.
I guess maybe the usage stats dont support making the profile selector better.
But also, maybe its a thing they would accept a change for?
For those few applications where I really would need profiles I will just open a different browser, so I still keep Edge/Chrome/Opera around for that rare situation. I don't need something that complicates my life every single click but it is the whole ideology of the Google Economy that they want you to spend 1% of attention on things that matter to you and 99% on things that don't.
As you yourself mention, Firefox has actual profile support, which may not be as good as Chrome's, but at least compare like for like.
While it is meant to be an alternative to Chrome's profile switching, it is more a workaround than a complete replacement. I need entirely different sets of extensions for personal, work, and school environments, something containers can't do.
Firefox's actual profile support is beyond terrible. To launch a separate instance, Firefox requires many more clicks than Chrome, all within a Windows-2000-style UI. Not to mention that there are weird glitches in their implementation.
Firefox is not usable for me until they actually spend time improving their multiple profile support.