On the other hand a manufacturer capable of designing and producing SHA-256 chips could be also capable of designing and manufacturing $other_commonly_used_has

On the other hand a manufacturer capable of designing and producing SHA-256 chips could be also capable of designing and manufacturing $other_commonly_used_hash_algo chips allowing for brute-forcing $other_commonly_used_hash_algo encoded passwords. The same manufacturer/design team could also probably prepare $popular_block_cipher chips. So, while BTC miner chips would not be useful themselves, having an industry capable of creating those chips is.