But why? Those things are easy to game, and speaking personally, I don't have an online software development presence like Github because I don't spend my off time working on anything I feel is worth sharing.

If i’m hiring for eng director in my industry I'm expecting at least a few 2nd/3rd common connections so i can backchannel. Without that i assume its someone who hasnt gotten along with anyone at beast or a scammer at worst

Numbers. I’ve read thousands of resumes over the past few months, screened dozens of applicants, and experienced a wide variety of weirdness and fakes both in resumes and on screen calls. Please note that I’m talking about raw “application box resumes”. Referrals and other semi-vetted sources don’t get this level of scrutiny.

I gave two examples of secondary sources, but what I’m really getting at here is that the numbers and noise are so, so high now (not to mention staffing firm fronts and foreign actors) that I usually need more signal than a solid-looking resume before investing even 30’ in a screening call.