Think how people come to the forums to find people to do everything in the game. Example: Looking for more for organized crucible matches. Looking for more for strike farming. Etc. A group finder would have that function in game. You'd be able to invite to fireteam directly and chat and then start playing. It's different than mm because it gives you a measure of control over who you play with. MM just throws you together with random people and you're stuck with them. That works fine for shorter activities like crucible matches, but long ones like the raid? Just no. And I know you want the option, but what you really want is a quick way to find people to play with. Group finder does that without the drawbacks of mm.