You don’t see why? Jeez it’s like 2012-2014 doesn’t exist anymore to some of you. Does nobody remember the state Spider-Man was in and the idiots behind the movies bringing the character down and dragging him through the mud?
I don't think Spider-Man was particularly muddy back then. A lot of fans and general audiences did like Garfield and Stone but also thought that TASM2 was too overstuffed with too many villains (I thought it wasn't, a 2 hour+ film having two villains and two or three cameos isn't overstuffed).
Captain America and gotg were bigger movies than Spider-Man.
Many film series do have diminishing financial returns.