The effort required to get someone new spun up on your project isn't trivial (unless what you're doing is trivial...). There is a lot to understand, both "hard"

The effort required to get someone new spun up on your project isn't trivial (unless what you're doing is trivial...). There is a lot to understand, both "hard" knowledge about the tech stack, product, specific features you're working on, customer use cases etc as well as the "soft" stuff, like communication style, the specific rhythm of the team and more often than not, reading a bit of politics. Never mind that this is stressful for the applicant (and would require them to quit their previous job for a perfectly insecure alternative), it takes a substantial effort on part of the existing team to do this. A commonly mentioned number for application success rates are on the order of 1:100. Even if this process is 10x better, a team will have to welcome a new "apprentice" every month (and fire most of them again) to get a single new hire a year. This is not obviously an improvement for either employer or employee.