what did you mean when you said it could create more collisions?
Blindly chaining hash functions could theoretically lead to increased collision rate.
Imagine that every hash function in the chain has a collision. That's mean that it transforms, say, 2^256 possible values into lesser # of values. For example, let's suppose it's twice as small for every hash in the chain, 2^255. So, chaining, say, 256 such functions will lead to very small target space, with very few possible block hashes.