All I can say is that your reasons never seem to change minds. You may find this difficult to accept, but most people subscribe to DNA Services for reasons other than Genealogy. The argument about not revealing RAW DATA was never the problem. They subscribed to 23andMe because of the health reports and AncestryDNA because of the Ancestry Reports. Or like those I kits manage, they did it because it helped me.
see 23andMe is finally allowed to tell you if you have the genes for Parkinson’s as to why people subscribe to 23andme.
and then contact these people and say
"The best reason for people to use WikiTree for this function is that it creates a bridge between GedMatch, multiple testing companies, and well researched user trees."
It goes right over their head. If you say it will help them with their genealogy, they can immediately say no.
Also, you should tell them that by adding a DNA Test, they are agreeing to "discuss and compare results with other WikiTree members?"
Many are not interested enough or at all in discussing their results or comparing their results.