Matchmaking usually implies it happens automatically which means a person cannot screen party members they just get "matched" and it is off to mission. You can get matched with people you don't want to play with. Instead just let us make our own parties. Functionally the same yes but the difference is in the execution

So is posting LFR on the forums, or making large clans to have a pool of strangers to LFG/LFR in. Thats the point. it's exclusion is nonsensical, it just takes extra steps to do something people are going to do anyway.