Since deactivating my Twitter account and moving to the federated Mastodon I’ve realised that for me at least I have no plans to join any social network owned by a single company. The exception to this rule is Glass, I pay a yearly subscription to use it and that’s ok. I trust the owners and my money means no ads or selling of my data.
If the service is free and I can’t get behind their privacy policy or reason for being then I see no incentive to joining.