you're starting a whole other discussion but...
of course no one really WANTS to purposefully distort their mix. but if you want something to compete these days, you're gonna do it. It's just absolutely impossible to get that kind of loudness with a limiter unless you want it to sound like absolute trash. clipping is WAY more transparent, at least for anything rock / metal.
and i'm not an expert but with the RTAS engine in protools, it does have headroom above 0. example, if you had a digi eq as insert 1, and clipped it by 6db, followed by a compressor plug, the audio being fed into the compressor would be +6db, not 0.