My point is there is no one way to play Halo. But the fact is Swat is and always has been a more populated playlist in each Halo game over Hardcore/MLG playlists.
Part of the beauty of the halo sandbox is how many cool game modes you can make out of it.
That being said, that is all SWAT is. It's a game mode that was popular enough to justify its own playlist. It firmly belongs in the same grouping as Infection, Grifball, Husky Raid, Castle Wars etc. It's another way to play Halo, but its not core halo.
That would be like calling gun game core CoD.
Popularity aside, MLG is closer to core halo than SWAT. MLG is just slight tweaks to the core formula.
SWAT just straight up removes core elements.
Honestly my frustration with SWAT is a lot of my friends were more casual Halo fans and preferred it to normal Halo. We would hop on and they would want to always play SWAT. I remember one even said that he never liked how cheap it felt for someone to steal his kill or for him to shoot someone first and them still killing them (nice self own).
I always wanted to play real Halo but SWAT was too popular :(