I am gonna take a wild guess and say that you don't know that many wedding photographers. I am gonna assume that the only wedding photographers that you have seen using gear have been at the odd wedding you have attended over the last 10 years or or at "workshops" etc.
Busy wedding photographers don't attend that many "workshops", they don't have time. I have been to a few workshops etc. over the years and usually use a 24-70 as it means I only have to carry about 1 x camera, but that doesn't mean I would use it for work.
I have been shooting weddings full time for 12 years, mid range zooms even back then were starting to get less popular. Wedding photographers tend to hang out in the same places both in real life and online so I know how a lot of wedding photographers work and the sort of equipment they use across the world. I could bore you with a list of reasons why I have more knowledge on this than you but I won't waste your time. There are lots of different types of wedding photographers and they all have different ways of doing things but for the vast majority 35mm is the most used lens by far and it isn't even close.
Off course there are a small amount that use a mid range zoom, they tend to be either extremely old school low budget type or complete newbies that made the mistake of buying into a lot of the nonsense you find online about how a mid range f/2.8 zoom is a stable of every professional photographer, the newbies soon learn though. There are hardly any of the old school budget type wedding photographers around any more for lots of different reasons.
An f/2.8 zoom is pretty useless for wedding photography unless you are going to use flash for everything. No client is going to be happy with having a flash being blasted in their face for all of the day. Often flash is frowned upon for the ceremony and rightly so. Clients expectations have changed a lot in the last 10 years or so, even more so in the last 5 years or so as well.
I genuinely have not spoken to another wedding photographer who is a real wedding photographer not some guy that shoots the odd wedding for beer tokens once a month in at least 10 years that uses a mid range zoom regularly. Lots of wedding photographers have one but it's mainly used as a back up lens in case the crap hits the fan. I have the 24-70 G.MII its a fine lens for a mid range zoom, I got it just after it was released, I have used it for the dancing a few times other than that have never used it, before that I had the Tamron 28-75, used it once at a wedding when I was having problems with my 35mm. Before that I had the Nikon 24-70 used it a few times when I first got it quickly realised it was pretty much useless and never used it again.