Genuinely, what else are chrome/edge offering that is a deal breaker for you?
Having a simple UI that you can just click and launch other profiles, really.
Unless you fiddle around with using different themes for each profile, or install kludgy extensions, there's nothing indicating which profile a window is currently using.
The thing is that it's a also problem that can easily be resolved with some small UI tweaks. Everything we need for first class handling of profiles in Firefox already exists, save a more intuitive UI.
It's a concept that is first class supported and easy to use in all othe browsers. There is just a ton of usability issues across the board, even with the third party addon.
From any browser window and any context, I can use CMD+Shift+M and either open a new window in a different profile, or switch to the first available window for that profile. The browser then clearly indicates which profile I am in and has some UI elements for it as well.
So it's just like any other core browser feature: having it being integrated into the experience directly, and being able to use it from anywhere, with a shortcut or clear UI element, is a much better experience than having to navigate to a settings page or use a bespoke application shortcut.
If having to open a bookmark always required opening a bookmark webpage, instead of the bookmark list or the url bar integrations, then that would be a much worse experience and certainly a reason to prefer one browser over another.
Most people like simple and boring UI which is straight forward.