Are people just stupid or do they not see marked enemies?

@GrizzGolf As said that either has to do with the lack of game sense of the majority of players. You would think that players could figure out themselves that a died teammate might mean there's an enemy in the area so best would be not to rush in for a revive, but instead secure the area first.
And then there's the issue of the still broken ping system where your pings are not visible to certain squadmates.