You make it sound like it's a big deal to write 10 lines of code before being interviewed. I agree that some candidates, possibly including me, would be put off by being asked to solve a problem requiring 10s of hours before interview, but we're not talking about that. We're talking about getting someone to demonstrate 10 lines of working code.

And if a potential candidate can't be bothered to do that, how bothered will they be to make small, uninteresting changes to working code? How interested will they be to fix a corner case they don't care about? How careful will they be about details when releasing code?

Not being willing to "jump through hoops" is an indication of fit, as much as many other things. My job is to make the hoops as big as possible, and as easy to jump through as I can make them. If people can't be bothered, then I guess I won't employ them.

Yes, it biases the selection process, but it's a huge save not interviewing people who can't, or won't, produce FizzBuzz (or similar).