I think the suggestion reflected a deep understanding that transitioning from decades of wild-west to standardized in the smooth fashion most likely to succeed would require that strategy.

If you don’t accept whatever some org’s data is encoded with, they won’t consider it a win for standards, or swap out whatever is producing that data for something more compliant. They’ll consider it a bug, and probably use some other more flexible processor.

On the other hand, if you can be flexible enough to allow quirks on import while not perpetuating them on export, eventually you and other software built with the same philosophy standardize the field.

I do think there’s a point where things are standardized enough that you can safely stop doing that—when all the extra quirk code is so rarely used as to be irrelevant—but I’m unsure if we’ve reached it yet. It would be something to actually analyze, though, rather than just a philosophical decision.