With all the “reliable “ glass nowadays, why is fixed a thing? Never seen the allure of a fixed scope, especially 6x..
When you always looking at hairy critters with the same magnification, everything becomes easier. Lots of 1-4 or 1-6 scopes these days, I have a few, the 1-4's never leave 4x and the 1-6's never leave 6x. Same with several other variables, they stay in one place.
If there is an advantage to more moving parts/lens/prisms, I don't know what it is.