That is sadly how Halo has been from the beginning. You will always have players with the mindset of “I will focus on kills while the lackeys (other teammates) focus on objectives.”
That’s nothing new I’m afraid, while I came in much later (Halo 3’s hay day), every time I played an objective game mode, players treat it like an unlimited slayer with a count down.
This is actually a problem in most games honestly. Way too many people will jump into team oriented games believing the only person that matters is themselves.
This will always be a problem as long as people think only they matter in team oriented matches too.