I do not use a 5% mite threshold because I think it is a universal rule. I use it because it keeps enough pressure on the bees to reveal useful resistance while still narrowing losses to a range I can live with.

Monitoring does not have to mean treatment. It can also mean selection. If a colony keeps mite loads low without intervention, that tells me something worth knowing and something worth breeding from.

If you treat everybody and monitor nobody, you are getting nowhere. The goal is not to win an argument about treatment. The goal is to identify which colonies are actually showing something worth preserving and multiplying.