> I have a Github profile with more than enough stuff on it
Based on my experience only, you're in the minority here. Most candidates I've interviewed have barely anything on GitHub. Some UI/UX-ish people will have a portfolio, which involves a lot of "view source" and isn't too rewarding. Lots of perfectly good working programmers have no active open source participation, not even a "dump of code" type of GH profile, making it difficult to tell wheat from chaff. Having them do code tests is pretty much the only way that doesn't involve talking to every single one.
Look at the other side, too: I've gone through hiring processes in the past as a candidate that started with a 30-45 minute conversation with the hiring manager, and proceeded to the onsite interview stage. This inevitably ended up being the classic 6-hour beatdown, with both sides muddling through without truly understanding what either is doing. These are usually so inconclusive (especially at bigger companies) that no one can make a decision, so they end up saying "no". Now both sides are 6+ hours in the hole. This could have been a simple 2-4 hour asynchronous code test, which would have provided hard information to the hiring team instead of the usual inconclusive bullshit.