replace "should" with "could".

I do think its wise to consider when a boolean could be inferred from some other mechanism, but i also use booleans a lot because they are the best solution for many problems. Sure, sometimes what is now a boolean may need to become something later like an enum, and that's fine too. But I would not suggest jumping to those out the gate.

Booleans are good toggles and representatives of 2 states like on/off, public/private. But sometimes an association, or datetime, or field presence can give you more data and said data is more useful to know than a separate attribute.