It's probably because of how few people actually raid (Destiny)

by General Vagueness , The Vault of Sass, Tuesday, April 14, 2015, 19:18 (3308 days ago) @ ArteenEsben

Seriously, the percentage of players that raid is incredibly small. This is true in almost all MMOs. While I think the raids have been, to date, the most interesting part of Destiny, I'm glad that the focus for HoW is on making content that is equally interesting but far more accessible. This looks like a good decision to me.

Of course, I haven't so much as launched Destiny in 3 weeks, so what do I know? Maybe the game is all raids all the time now.

I'm sure more people would raid if Bungie actually made it easier to do so. Be it matchmaking or even just an in-game LFG.

They could even do something more straightforward and natural than that, like, I don't know, let you talk to anyone in any game mode without having to do external opt-in party stuff.