The assumption you're making is that everyone who is capable of doing a dev job manages to get one, so if you remove all the hiring biases all those people will continue to get dev jobs and nothing will really change.
That assumption is wrong.
There are thousands of people who can't get dev jobs for reasons other than lacking technical ability. Some hiring managers filter out candidates before the make it to interview for absolutely stupid reasons. Some companies have hiring practices that are plain stupid and select out capable engineers for dumb reasons. If hiring was a multiple choice exam those people would be able to enter the industry and there'd be fewer companies with unfilled positions.
Also, even if you don't think it'd have much of an impact on the numbers across the industry, the numbers at the specific companies that have bad hiring biases obviously would change. That could be useful.
The assumption you're making is that everyone who is capable of doing a dev job manages to get one, so if you remove all the hiring biases all those people will continue to get dev jobs and nothing will really change.
That assumption is wrong.
There are thousands of people who can't get dev jobs for reasons other than lacking technical ability. Some hiring managers filter out candidates before the make it to interview for absolutely stupid reasons. Some companies have hiring practices that are plain stupid and select out capable engineers for dumb reasons. If hiring was a multiple choice exam those people would be able to enter the industry and there'd be fewer companies with unfilled positions.
Also, even if you don't think it'd have much of an impact on the numbers across the industry, the numbers at the specific companies that have bad hiring biases obviously would change. That could be useful.