[redvenom]

I think there is also a difference between lock in and just using a service. If your primary email is Gmail, it's hard to switch and it's worse than YouTube. With YouTube, if Google decides to lock you out, you can more easily move to PeerTube or another service. I also recommend that if you create content for YouTube, you also upload it elsewhere.

[jimmaswell]

Switching from gmail and forwarding to your new address sounds easy unless you insist on deleting it and changing every account referencing the old email.

[arsenico]

Forwarding to a new address doesn’t solve the whole Google problem, as GMail still stores and processes all your emails.

[beached_whale]

Your final point is the pertinent one. Without content elsewhere that is interesting and easy to find, there will be no alternatives.