In which context would somebody try to reverse a hash? That would be like arbitrarily enhancing a bad-resolution image to see something that cannot be seen.
Hash collision should always be about finding matching content for a hash.
Hash collision should always be about finding matching content for a hash.
Cracking sha256 hashes implies trying to reverse a specific hash. There are literally thousands (millions?) of potential inputs that hash to a valid bitcoin mining block output. It's basically a race to find the first one matching the rules of the current block difficulty. The goal isn't to produce any one specific input/hash pair.