These blanket statements aren't necessarily true.
If you are looking for a very small add on at any resort, direct might make sense due to the lack of smaller contracts on the resale market, the slightly lower closing costs buying direct (which on a small contract can add a few $$/point), and the overall $$ savings not being all that much at certain resorts on a small contract (30 points or so with a $20 direct premium only comes to about $600 in savings vs the same $20 difference on a 200 point contract is $6000).
If you are looking at a resort like VGC, where resales are few and far between, esp if you are looking for a specific UY and # of points, direct might make sense. I just saw a few VGC resales listed at $140, $150 and $165 per point! Direct is $165 and last I checked a couple of months ago there was a $7 incentive for contracts over 50 points. Of course you might have to go on a wait list, but I did that, then continued to look at resales while waiting, and wound up buy both direct and resale with a couple of months of each other.
As for "sold out" resorts, Aulani is not "sold out" yet there are plenty of resales, some at attractive prices, that might make sense rather than buying direct. Heck, even VGF has had resales with asking prices in the $130s. There might not be a lot of contracts out there for VGF, but I would certainly encourage people to consider looking at those to see if they meet their needs before committing to buying direct, esp if it's a large contract.
Finally, if you REALLY need to finance the purchase, Disney makes it quite easy to qualify. Not saying this is the right thing to do, but for some, buying direct might be their best recourse given this factor.
There are many factors to consider in the direct vs resale question. How loaded is the resale contract - those extra points have value? Is the price differential worth the ROFR wait? Is there a long wait list for direct points at the resort and UY you would want if buying direct? Do you need to finance, and do you have access to a line of credit or Disney your only recourse if you do? What are you going to use your points for - most here would advocate the best use it at DVC resorts, while others have used their points many times for cruises and other uses for which only direct points would qualify?
Each buyer needs to assess his own situation to decide what works for them. There are a myriad of factors to be considered in making such a big financial outlay.