why have p2p HD groups flourished?

As I grabbed the latest WiKi release that beat the scene in time and of course quality, I wondered why p2p HD groups have flourished?

It seems that very few p2p groups were involved with xvid or dvdr. Sure, there were a few touching up cams or ts releases. And there are still plenty of homemade dvdrs on dedicated trackers.

But nothing compares with the last year or two of x264 encoders.

It's a given that the main reason is the lack of quality in scene encodes, but maybe there is something else at work.

Is it a part of the growth of x264 in popularity? Is x264 the new plateau? More affordable ways of playback (i.e. cheaper hdtv/monitor and definitely media players)?