I think the problem is not that they didn’t have a clear direction for the big bad (look back at the Infinity Saga, Thanos is barely spelled out and there is very little overarching continuity towards leading up to IW/EG) I think the problem is that most of what you listed are just mediocre to not good. Out of all of those, I would probably only count the following as being good to great:

• Spider-Man: Far From Home
• Wandavision
• Loki (both seasons)
• Shang Chi
• Spider-Man: No Way Home
• Werewolf By Night
• Ms. Marvel (on this one, I might even be fudging a little just because I love Iman in the role)
• Guardians of the Galaxy 3
• Marvels*

Out of roughly 22 on the list there, that’s a just impressively bad hit rate. Not everything I left off of my list is “bad” per se, but it’s mostly just mediocre and I have about a zero percent chance of rewatching it (Falcon, Ant-Man 3, MoonKnight, Dr Strange, Wakanda, etc.) compared to the Infinity Saga, where I’ve seen just about everything multiple times. And then there is the problem that quite a lot of it is bad (Eternals, Thor, Secret Invasion…) I think doing this much TV really hurt them as quite a lot of the TV properties were poorly thought out and didn’t have 6 hours worth of good story.

I don’t think that the idea that having all of the tie-ins really hurt them as much as the perception that all of the tie-ins were required watching hurt them. For example, The Marvels you can totally go in without having watched either of the TV properties, or probably even Captain Marvel. The movie guides you through what you need to know, which is very little, but that is a theme on basically any comment page or article when you talk about the film’s box office draw. I mean, we’re not talking about Breaking Bad or the good seasons of Game of Thrones where if you didn’t watch from the beginning you’re going to miss big moments.

and re: your point 2, this is also the case for the MCU Carol. The movie was among the worst in the IS, and while Brie Larsen is a fantastic actress, we’re several outings in before you can even kinda care about Carol in the Marvels. Ironically, I counted this as a plus for the movie when I was telling my buddy if he should go see it. I saw Endgame opening night, and the audience was right there for all of the big moments, which you can tell they intended Carol’s destruction of the ships to be, and while it wasn’t quite crickets, you could tell that didn’t hit the way they wanted it to. Even this movie, I went to see in spite of it being a CM movie if anything.

* This one might be recency bias or maybe just that the MCU has been so disappointing that I’m grading on a curve a bit, but I would give this one a solid 3/5.