Ignore these people.
Use as many polygons as you want, as long as the result looks good.
The issue is that if you use too many polys in a gun, it ends up looking cluttered. It's a stylistic limit, not an actual one.
The thing with polycount is that it has no actual impact on gameplay/function, but it generally corresponds with the style of blockland to have a low polycount
The idea is to have as low of a polycount as possible, so using hexagons or octagons instead of 12-gons or whatever.
Frankly, Zeblote, I'd like to think I'm
more qualified than you are to talk about this
Edit:
I don't mean to be rude, but I don't think it's fair to discount someone's opinion, especially if it's perfectly valid.