I've noticed the same thing. It's like they are two COMPLETELY different mindsets.

We used to use the same DVD replicator as one of the very largest gay adult producers. Through a brilliant screw-up by our replicator, 200 pieces of our title "Tastes like Twinks" got manufactured, DVD disc art printed, packaged and shrinkwrapped... but actually contained a leather title with fisting in it produced by said studio.

Needless to say, the customers that bought the defectives weren't pleased... but the interesting part was that the replicator let slip that the production run for that title was about 15,000 pieces. And that was well-marketed popular title for one of the very largest studios.

So what these DVD studios don't get is at maximum, they will get 15,000 sets of eyeballs, plus maybe a few thousand more from rentals... while the online models get all the cycling through of members of a given site PLUS all the visibility of all the affiliates promoting said model through galleries, etc.

I think it's probably a case of "old guard" people not realizing how much the market has changed. And unfortunately, they probably won't get it until their way of doing things is either completely gone or so marginalized that the revenue model no longer makes sense