The problem was (and is) that anybody could publish a blocklist, and not everybody did so with good intent in their heart. Some people lied about their own listing criteria -- not following their own published rules (which is weird given that they were free to define those rules) and some other people were just plain jerks. This was before RFC 6471 existed.
Nowadays, the world has mostly moved on from blocklists. Spamhaus is still out there, having effectively transitioned to a modern security vendor, still widely respected and broadly used, but many other blocklists have closed up shop. Thus, Blocklist Resource has become something of a "blocklist graveyard" at this point. I keep it live so that people wondering if blocklist XYZ is dead can find that info.
Remember that in these modern days, blocklists don't generally cause deliverability issues. With the exception of Spamhaus and just a few others, being listed on a blocklist will have no impact on your ability to deliver mail to any of the big mailbox providers like Gmail, Hotmail, Yahoo, etc. None of these big providers subscribe to random hobbyist-driven spam filters with goofy names.