I haven't looked at other teams but I think the same can be said about them and developing catchers.
Catching is very difficult to produce and it is probably the most difficult because of how difficult the position is. A good catcher who can both hit and play defense is like finding a HOF QB in the NFL.
The Brewers since 2012 have the 6th highest wRC+, 5th highest in oWAR, 1st in dWAR and 2nd in WAR. I would say that is pretty good. Notice a team that has a HOF bound catcher is only in one of these lists.
While the development of the players haven't been all that great the results the Brewers have been getting at catcher have been phenomenal since 2012.