I understand that password hashes like bcrypt have the principal property of taking a long time to run, but I'm wondering what if anything about password hashes make them superior to merely running a fast cryptographic has a bunch of times.
In particular, why does bcrypt exist when I can just run SHA-256 100000 times? Furthermore, it seems relatively extensible to adapt to increases in computing power. When computers get 100000 times as fast as they are today, I can just reapply the hash to my password hashes 100000 times and at verification time run SHA-256 100000*100000 times to validate a password attempt. Are there flaws in this naive approach. Are there other properties of password hashes that make them particularly suited to hashing passwords? Lack of parallelizability, space complexity, something else?
My question comes about when analyzing a prominent response to the June 2012 incident in which 6 million password hashes were stolen from LinkedIn. In the article, the author emphasizes the value of using a password hash instead of a fast cryptographic hash in validating user passwords. I understood the basic argument for having a hash that's slow but failed to glean from it particular advantages of "password" hashes that made them distinct.