No, the lock in is not needed for seamless behavior. The lock-in is to secure various revenue opportunities.

For example, if I connect a displayport cable to a displayport connection, poof, display happens. There's no 'tinkering', there's no "trying to match vendors", it just works.

Similarly, here folks sorted out the protocols in use, and none of the 'seamless' users were impacted. VW went out of their way to break them not to ensure a seamless experience, but because they wanted to paywall capability in a reliable way.

One could easily imagine schemes that didn't require the lock-in, but would not assure an enduring revenue opportunity.

And you can't have this with open standards..?