That's true, same reason why I wouldn't like to share an Apple Account on there due to the high integration. While I use Google for pretty much everything, I don't use it for smart devices; all that for me is done with Apple HomeKit mainly, so joining another family has been fine otherwise. No issues with YT, Maps, Gmail, Google Photos, Drive or Google Calendar, thankfully, all that remains private, and I can't see anyone else's.
Looking at when I started paying, and it's been 10 months, and so far it's been great. I joined an existing family, and Sharingful just bills my bank account automatically each month for £4.60. Families do seem to fill up quickly, though you could always make your own and hope others join in quickly to split the payments.