[coldtea]

>2. If someone falls behind on their assigned story quota, how would a manager know whether that is because the story didn't meet the criteria in item 1, or because the person isn't putting in sufficient effort because of OE or other commitments?

They could expect to know the reason this happened (e.g. prerequisite not ready, this design issue is not solvable so we're testing alternatives, etc.).

And if it happens often, they can always fire the person.

To return your own question: "If someone falls behind on their assigned story quota, how would a manager know whether that is because the story didn't meet the criteria in item 1, or because the person isn't putting in sufficient effort?"

Whether that's because they just slack off, or because they don't have the skills so everything takes extra time even though they work hard, or because of "OE or other commitments" is irrelevant, isn't it?

Besides, it is not just "other employment" that would have such a concern. The same is true for e.g. trying to build a personal startup MVP on your spare time or building a simpler passive income side-gig, both things which HN crowd loves, and which employees should totally be allowed to have (and lots of IT success stories wouldn't be possible if they weren't).