> If we admit it's a job that a computer cannot reasonably do, then why do we have a computer doing it in the first place?

That's not what you said. You said if it's a job that can be reasonably done by a human, then a computer should be similarly effective. That's clearly false.

> if it has limitations that are significant (and frequent!) enough to cause a large controversy.

Controversies are not necessarily a sign that a problem is significant. Consider all the "war on Christmas" nonsense.