How necessary is a zerostat gun?

Agree if a lot of static or LPs attracting inordinate amount of dust you could use on. Otherwise they are no needed.
I do not need one.

In So Cal where the humidity can be on the low side I find it necessary!!!

Not needed unless you get a lot of static. Doesn't work on children.

I have the Ionoclast and use it regularly on vinyl and cd/sacd/dvd-v and dvd-a. Since you can hold a cd in your hand while using the Ionoclast it is possible to feel the difference in static release. It makes the whole front end smoother and it makes me feel better. Just part of the process. Listen every day.

I hope not very.

Haven't used one in 30 years.