They're starting to gain more in popularity. It's kind of sad, really, because I don't think a lot of people outside of this site are prepared for how monstrously big these guys can get.
have you heard of a liger? its a lion mixed with a tiger and they get 3x the size of either parent, they call it hybrid vigor. there are a few discussions on here about it. ill give the lfs the benefit of the doubt maybe they dont have the full grown size upon sale because no one knows when they will stop growing. there are a few members on here with some pure brutes, but how many people have 15-20 year old monsters full grown? none that i know of. so maybe thats why the lfs doesnt say how big they can get, they dont have the slightest idea.