Would you say the MCU has had a single flagship character up until now? I'm not sure it has. Good argument for Iron Man, but equally good arguments for Captain America.
So yeah I definitely agree that Marvel doesn't need a "face of the MCU".
I have to qualify my claim that they are setting up Spidey to be the new face of the MCU. Iron Man, as everyone has been pointing out, wasn't really the face of the MCU either--as in
the face. But he carried that role jointly with Cap (as hef pointed out) with Thor slightly in the background. The main poster for Infinity War had Iron Man front and center and the main poster for Endgame had Cap instead, which represents their joint flagship status. And the finale and denouement of Endgame held Cap and Iron Man equally in the spotlight.
Anyway, I do think that Spidey is now set up to be one of the faces of the MCU alongside several others. I don't think anyone will feature more prominently than him but others will certainly be tied. I could definitely be wrong, but as far as I can tell, he's presently tied with Dr. Strange and Black Panther for flagship status. Ant-Man looks like he'll remain a fun background character, same with as the Guardians (whom Thor will be joining). It's hard to predict what they'll do with Captain Marvel. It could go any way with her. I could see her taking what was Thor's status as an extremely OP and popular character. (Remember Thor didn't become extremely popular until his third solo movie.)
As a young actor, Tom Holland is poised to be in the MCU for a very long time, perhaps longer than anyone else ever was or will be. I heard the idea floated that they should do a high school trilogy plus a college trilogy, which is fine by me. He's already featured prominently in two Avengers movies and Civil War. But even Iron Man only had three solo movies, so I could really see them making Spidey
the flagship at some point in the future, even if they take their time getting there.