think you shouldn't be able to place blocks over the pit.
I agree with this. It seems to me like it is too defensive of a strategy which does not improve the dynamic of games. There is no nuance to it; it is just piling as much as you can on top of the pit.
It is a very centralizing strategy as well since there is not repercussion to using it. In CTF, having a large flag defense made it harder to return you own flag, but in brigdes, your pit defense does not affect your team's ability to score.
Also, the game is defined by the bridge - it is literally the name of the game. Therefore, it would seem that the strategy should be to place and break blocks on the bridge which aid your team in getting to the other side but hinder your opponents, instead of focusing on throwing people at a mound of blocks and hoping some squeak through.