I'd argue, that for some, CLI path is actually cleaner.

You see, the way described above creates entirely separate points of entry, and you don't have to go to the central menu to launch specific profile.

It eliminates one step (Profile Manager, about:profiles or whatever) allowing you to get faster to the desired profile - same way you'd launch a default profile.

It's logical separation too. It's like separate browsers from UX standpoint (they do use the same distribution though ...unless they aren't - you can configure different distributions for different profiles - nothing stops you from that).

I'm just leaving the information about the gui option to other who may not be aware that it can be done from the gui too, and think its difficult to do in Firefox.