So? If you knew what you were doing, you've been able to put 10s or 12s in reg cab trucks for the 17ish years I've been into this.
Just because you can doesn't mean you MUST, SHOULD or NEED to. A lot of companies don't make 10s either. That must mean that you're stupid for thinking 10s are good.
6.5s can get just as low as an 18. I think anyone that uses anything bigger than 6.5s is stupid. Anyone that has an opinion different than mine is stupid. Anyone who has a different goal for their system than me is stupid. Anyone who wants something different that what everyone else has is stupid.