That depends a lot on the platform. On MacOS, for example, switching to a profile from about:profiles results in the new window being open in the background and it would mess your Firefox icon on the dock. The solution used by Windows and Linux users (the -p command) also doesn't work here (maybe it does via the terminal, but not with shortcuts).
Anyway, there's no benefit to Firefox or its users if profile switching is ugly or clunky. They're improving this and that's a good thing for everyone.
On macOS, sending `--no-remote -P <profilename>` in the command line is the method for launching specific profiles.
I add an icon (slightly modified for each profile) to the script, and rename it to (e.g.) ~/Applications/Firefox-work.app for convenience. Works from the Dock, Finder, Spotlight, etc. I usually launch from the command line, but all the usual ways do work.
Improving the profile switching experience is great of course. But the above workaround has served me perfectly for as long as I can remember. Obv would not work for everyone.
Anyway, there's no benefit to Firefox or its users if profile switching is ugly or clunky. They're improving this and that's a good thing for everyone.