I don't believe muscularity has anything to do with finding nerve or pressure points which are close enough to the skin to find, hit or apply pressure. The reason that pressure points are not used in mma is because in the heat of battle it is virtually impossible to pinpoint your attack and effectively use the concept. It is unrealistic unless you have honed your skills over most of your lifetime. Maybe George Dillman or a Dim Mak master like Earl Montague could possibly pull it off but not the average mma practioner who wants to find an edge on the competition.
One more point, during a fairly static situation where one fighter is on top of the other you would think the opportunity for a nerve strike would arise. But just think of the adrenalin that is flowing and the fatigue factor. First, the adrenalin would obstruct much of the pain, a seasoned mma fighter is much more used to withstanding pain via submission than the average guy in the street, and second, fine skilled motor techniques are very difficult to pull off under such a stressfull fatiguing situation. Finding a dime or even quarter sized spot on a sweaty whirling dervish is a tall order.
Bottom line, you don't see anything in the octagon that isn't practical, doesn't work or pay big dividends.