Sometimes yes, sometimes no. Are you seriously trying to tell me that the BEast was not the best conference in 2008-09 when UConn rolled through everyone in conference play, saw six other BEast teams in the Tourney, and met Louisville in the NC game? Same thing in 2000 when UConn towered above the BEast on the way to the NC and the conference went 13-3 in the Tournament. Top-level action within a conference breeds both competitiveness and success in Tournament play.
A bunch of conference teams beating up on each other in closely competitive play can strengthen the teams if they have a high-level of proficiency, but if they're just a bunch of flawed teams reinforcing each others' weaknesses, then the teams won't be getting better and none will get to the FF, if you get where this is going.