Giving as few reasons to deny your application before an interview just seems like good practice. The whole process is arbitrary anyway.

This depends on how many options you have. If you have many options it can be a good thing to filter out companies that would not be a good match for you.

As a general rule of thumb, if you don't want to be evaluated at least in part based on something, don't put it on your resume.

(and the inverse holds as well: if you do want to be evaluated at least in part based on something, consider putting it on your resume).

Still, I'd be pretty irritated to learn that someone decided not to even talk to me because I included a github link to some toy project that they didn't like.

This strikes me as unnecessarily bitter and cynical. Application is a two way street. Would you even want to work for a company like that?

Not bitter at all, not sure where you got that impression from my post. If I have something that does not present me in my best light, why should I volunteer to show it in a hiring process? I am just being practical.

I do think all hiring processes have a component of arbitrariness, so I don’t think it is necessarily a bad sign that a company quickly dismiss candidates from poorly-maintained GitHub accounts. I would gladly not show my GitHub and try to get the job showing my skills in some other way.

A company doesn't necessarily begin and end with the person hiring.

Most people work where they find work, not where they want to work. It's less true in IT, but I'm still betting it's mostly true there

If they pay well – absolutely.

There are risks either way, and this is one of those processes where you just want a single good hit. So I guess the optimal course here is to maximize your risks (unless they are biased into not-hire), not to minimize them.

There are other processes where you must never fail. For those you want to minimize risks. If you want a job at X and nowhere else, this is your situation. But that's not very common.

Good point

What’s more common - hiring managers who see the inclusion of a GitHub as a small positive signal but don’t scrutinize heavily (or even more likely don’t bother to click into it), or those that dig deep and scrutinize open source contributions as a primary decision factor?

Or maybe the managers will decide to only interview people with a GitHub link?

Could go either way.