People who are consciously trying to de-couple from big tech are the same people who are conscious about lock-in effects.

There isn't any lock-in using a Helm. You can always access and export your data on the LAN using standards-based clients to get your data wherever you'd like it to be.

You say "standards-based clients", does this mean I do not have direct access to the filesystem? Or a shell account for that matter?

Using email as an example, having to transfer email with drag'n'drop in something like Thunderbird is clunky, slow but works to a degree.

Having direct access to the mailbox directory on the filesystem would make it easier to transfer out/in (assuming you already have your emails in the same format).

Arguing with people who are trying to tell you how to market better isn't going to help you market better. Quite the opposite.

Not only that, those are one of the big reasons for the migration away.