"Console Spam" Thats not even close to why they are horrible to use.
The reason why the Propmod is crap is because of how much rendering is required for one model.
In RTB v1.045 and Vanilla, the bricks were made by objects. We could only have about 130 bricks in a server before the lag became too extreme to play. Coincidentally, servers can now support about 130,000 bricks.
This is because models require about 1,000x the computation power required to render as bricks do (Source: Trader, informed by Badspot). So unless the models are actually doing something fancy (vehicles move, players do player stuff, doors open and close) then they're just seriously wasting your resources.