lmatthews...

If you have issues with the possiblity of a syncing feature, and based on your arguments against it, I'm trying to figure out why you are on this site. This site hosts online family trees, which you state you have an issue with.

It would be a tremendous benefit to those of us who WANT to post online. To those of YOU who do not want to post your tree online, then your choices would be either...

1. Do not use the feature to synchronize data.
or
2. Do not use Family Tree Maker.

/rant on
Based on your 'complaint' with the idea, you probably should also avoid uploading any gedcom data without first removing all living people entries entirely. And for that matter, do not browse the online trees, as they may contain names of living people. As living people frequently appear in searches for the deceased, I'd also avoid doing any research on the deceased to avoid accidentally finding information on living people. And with the restrictions you have now placed on yourself, based on your arguments, you have ruled out living and otherwise, your best course of action would be to refrain from the hobby of genealogy.
/rant off

The submission agreement would (if this feature is implemented) be displayed prior to the first use of this feature, and the only things different from deleting your old tree, exporting a file, creating a new tree, and uploading your file is ALOT less broken links to deleted trees when those of us that do, are searching member trees. That, and less having to add all ones relatives to the new tree every time you create a new tree to update your work.

If you want to get more technical, you could probably also add alot less re-uploading pictures with the new tree, as deleting the old tree means you'd have to manually attach them again to the new tree's people.