I can't hear much between 21.5kHz and 22.05kHz...
Much? How about nuttin' at all?
But you never know, you might someday need to master something specifically for bats and dogs. Don't forget Go Go!
I suspect a lot of sales of mastering tools are the result of envy. Envy of other people who use something different to get good results. If {Famous_Engineer} uses limiter X, then I also need limiter X to achieve the same quality. In reality, I don't. All I need is to acquire one versatile high-quality limiter and then take the time to learn it well.