You do realize that
1) you have no way of knowing how many are posting there with the signature disabled
2) doesn't change the fact that 72% of my sample had NO signature (a far cry from the superlative "everyone", "all", and "everybody" language you were using)
3) I'm betting that most posters are smart enough to figure out that they can list the phone(s) they use in their board signature so that they can disable the stock "free advertisement" sig emanating from their phone/app. It's really not that difficult.
If you are posting on that forum from a computer, how do you denote in your post which device(s) you are using?