The truth is that people will use threads. Why? First of all they are the best solution to certain classes of user interaction problems. Also a lot of people think that they are cool. And programmers who are used to languages or environments where you thread everywhere just find them familiar. Therefore it makes sense for p5p to try to support them.

What I would like is for people to not get burned by using threads where it doesn't make sense to.

For one description of why it sometimes doesn't make sense to use them, see Threads vs Forking (Java vs Perl).

What I would like is for people to not get burned by using threads where it doesn't make sense to.

Then perhaps answering Don't. isn't the appropriate answer to a question asking for Best Practices?

Best practices are practices that are right most of the time that someone is trying to do something.

My (biased) opinion is that most of the time that people are trying to use multi-threading, they shouldn't be.

Therefore Don't. is perfectly appropriate for a best practice. (IMO.)