I'm surprised that greylisting still works, to be honest. But the blacklist services never did, at least if your goal is not to reduce spam per se but to make or keep email useful.

I disagree. URI blacklists in SA have stopped a ton of spam from reaching me with nary a false positive.

Not true. If you cut down the number of preforked processes and use spamd spamassassin works just fine in a VPS with limited memory.

Also, SA leverages blacklist services (and other techniques, it's very configurable) and is easier to integrate into your mail server.

SA is easy to integrate in a mail server but not "easier" than adding one line to the server configuration. SA lets many spam go through, it's a pain in the neck to fine-tune it and when you have a lot of spam coming in it uses a lot of CPU for parsing. With blacklist servers spam is dropped at the beginning, there's no further parsing etc.

Basically I don't know why anyone nowadays would use spamassassin (I've used it in the past) when there's graylisting and blacklist servers that work wonderfully with low overhead.