Imagine a future where babies can be incubated in an external enclosure, rather than a womb.

This doesn't seem too unlikely. I've been hoping tech would go this way -- We're doing IVF in June, and it's still hit-or-miss whether it'll work.

In that future, if someone identifies as nonbinary but still wishes to have a child, neither "mother" nor "father" would accurately describe them. And since a womb isn't required for a baby, there's not necessarily any "mother" (nor "father") in that scenario.

That said, I think the argument is "mainboard is better than motherboard for the same reason that denylist is better than blacklist -- the whole point is so that people don't have to be reminded of social issues whenever the word comes up in discussion."