The other thing is that many people who call themselves "wine makers" reject mead and cider as inferior beverages and don't branch out and do different things. I'm basing this on a large wine making club here that has no interest in brewing and few members who have brewed. It is my understanding that the reason the BJCP has mead and cider guidelines in the first place is that the wine judging community was not interested in judging them. They are wine snobs.
This is different from homebrewers who make beer, wine, mead, cider, sake, cheese, vinegar, etc. Not all brewers do all of them, but they usually get interested in trying other things. Maybe this is because with a basic brewing setup you can make pretty much any fermented beverage, but if you have a wine making setup you need to buy a bunch of stuff to make beer.