I've posted this before, but I think the most important driver behind the crackdown on commercial renting is the 11.5% resort tax.
Anyone who is in the business of renting out resort rooms is obligated to pay the tax. Disney pays the tax on all the rooms its rents out.
It wouldn't surprise me at all if the government bodies told Disney that they expect Disney to collect the tax from the owners who also rent or prove that the amount due from this activity is negligible.
I don't think this is about member complaints about availability. I think it is about the money.
I susupect this does play a role in this.
I also agree with DOC that WDW DOES have an obligation to COLLECT the tax and FORWARD said tax to the State.
DVC received some form of notification or warning IMO. It wouldn't surprise me in the least if the point morphing and lack of tax collection on rentals both had a large role. Both are illegal.