I agree totally. No tree and private trees just hit the no confidence bucket. Not one person with a private tree has ever replied to my query.
Further, I have spent a great deal of time scanning in documents and photos to share. I hope that my work may someday benefit someone else. Isnt the purpose of genealogy to grow your tree? Hiding your proofs for your 3rd GG isnt a privacy matter. It is simply dog in the manger. If you want privacy keep all living people off your tree.