Two different movies. One is a film about a team wHile tHe Avengers is a groundbreaking film wHere tHey combined 4 separate films into one sequel of eacH films protagonist. THis Has never been done before and now Has started a trend for tHis.
Yes Avengers tHe gimmick of "look four separate film cHaracters are togetHer, " but now otHers want to join tHe van wagon.
Now we Have tHe gimmick "Look Superman and Batsman are togetHer on tHe big screen WOW! Never been done before"
A better comparison would be tHe X-Men film, FF film, and tHe GotG film because wHat tHe Avengers film did is monumental and otHers are desperately trying to catcH up.