Yes but if the cover is legitimately terrible, and they could be performing a song of their own in place of the really terrible cover, the criticism is completely warranted.
I'm sure they didn't set out to do a terrible cover, and it's a matter of opinion because I heard a bunch of people singing along and clapping. Or, a band could choose to play one less song in their set. It's not like they went into studio, recorded it and everyone hates it. Criticisms of all these live covers have gone overboard on this site.