critics once again rating Marvel on a curve.

Doesn't seem the general concensus in the reviews I've read.  And in the context of what the film is - a comic book blockbuster - rating a film highly because it succeeds at being fun and entertaining seems fair enough.

Maybe Marvel actually are making films critics do enjoy.  Is it that hard to believe?  You or other individuals may not like them, but it's a far more believable  reason for their consistent good reviews than thinking, like some do, that Disney is one big bribery machine.