Wouldn't you be worried about a bit of Marvel fatigue? I certainly feel it. Infinity War and Endgame were epic. And I love love loved Far From Home. But I'm ready for a bit of time off. I can't be the only person out there feeling that way.
I think their waiting is a combination of avoiding what you are talking about, while also leaving some level of finality to the end of The Infinity Saga. I feel the quicker they could have just jumped right in, the less of a finale Endgame would have felt like. I also think them wanting to avoid spoilers to Endgame also played into this lull on the back end of it. If there was a bunch of movies lined up behind Endgame, production, announcements and leaks would have been inevitable prior to Endgame, and they didn't want any of that.