Phase 3 of the Marvel Cinematic Universe straight up delivered the goods. Years of build up finally culminated in one of the greatest two-part sequels ever produced.
Avengers: Infinity War and Infinity: End Game sucked everyone in as the conclusion of the original Avengers was told. The phase ended with Spiderman: Far From Home which was perfectly fine.
Phase 4 never had a chance. Just like the old saying goes, “you never want to be the guy to replace THE guy.” There was no way Marvel was going to be able to live up to the hype they just pulled off.