I don't think it makes sense to conflate vendor lock-in with taking a dependency on a given technology. Do we then have "Linux lock-in" and "Postgres lock-in"? The term "lock-in" shouldn't be stretched to cover this concept imo.

It’s not quite the same thing as a commercial vendor lock in but it’s close.

You can have Postgres lock in as much as Wordpress has MySql lock in.

I agree that you have less Linux lock in but Docker still requires a Linux kernel everywhere it goes. BSD need not apply.