Iron Man + Spider-Man + Doctor Strange + Mantis + Drax + Quill seemed like they basically beat Thanos with 4 or 5 Stones in Infinity War if Quill wasn't a dumbass. Maybe I'm forgetting someone but that was roughly the group. Nebula might've been there. Anyway point is when the final battle is those 6 of 7 + a bunch of other people vs Thanos without the stones it feels like we're de-escalating a bit, especially since the army scenario was basically the ending of Infinity War.
Anyway honestly I didn't have much of a problem with the scene, liked it even in a "hell yeah these guys are badasses doing badass things" kinda way, so this is kinda nitpicking don't get me wrong. I'm just explaining why I kinda was hoping for a bit more somewhere, why 'just' fighting Thanos kinda stopped doing it for me as much after 2 long movies with a bunch of cool fight scenes.
Them beating him was entirely contingent on Mantis though. Remove her and throw in extra people who are better fighters and they still lose