- the entity number (3)
- the kind of entity (Cats)
- the kind of part (Legs)
and that's not a huge number of combinations.
Yet they still need to be typed on cell phone keyboards, TVs, or communicated over phone (shared passwords are the best compromise if asymmetric cryptography is not an option), in which case you usually need to spell it out anyway.
curl https://raw.githubusercontent.com/danielmiessler/SecLists/refs/heads/master/Discovery/DNS/dns-Jhaddix.txt | grep "horse-battery-staple"
There's a well-known reason for that (and for GPs comment): https://xkcd.com/936/
I maintain that a good secrets management system has a number of passwords which should be memorizable (and memorized) which is greater than zero. Possibly by only one element.