gamestudio's physics engine ODE uses an O(n^3) solver by default. this means that performance and memory usage scales cubically with the number of touching physics objects. so the number of physics objects in a stack is quite limited as you can imagine.

in older engine versions a stack overflow caused an engine crash in such cases but now there seems to be some safety mechanism to prevent that. freezing physics isn't that great either though.

other physics engines use algorithms that scale better but you can't really do a house made with thousands of bricks with them either. it still takes to much processing power. additionally many engines only can achieve algorithms that scale better by using cheats that lead to more unrealistic physics (spongy objects, jittering, clamped mass ratios,...).