DES crypt(3) isn't a block cipher. It's a (crappy) hash that uses the guts of the DES algorithm. Don't think of it like AES or Blowfish or whatever. It doesn't "encrypt" passwords. What it specific does is encrypt a single all-zeroes block using a key derived from your password. There are, for what it's worth, a lot of hashes that are --- in the heart of hearts --- block ciphers. Some of the SHA3 finalists fit that mold.

People are very confused by this whole "Gawker is using DES" narrative. But Gawker isn't "using DES"; they're using DES crypt(3), which is a construction derived from DES internals. That's not at all the same thing.

In this specific case, because DES crypt(3) is in fact a crappy hash, passphrases are irrelevant; crypt(3) truncates them to fit a DES key. The rest of the data for your passphrase is never even hitting the hash, so a stolen hash can't possibly disclose the whole passphrase.

Thank you for your answer, I understand now.

I think systems generally only use one block, and so ignore anything after the first 8 characters.

Even if they were to use multiple blocks, I think most simple ways of doing that would only add linear difficulty to cracking rather than exponential.