Let's accept your basic premise, that it provides a meaningfully strong positive filter. We only get better software if the people who don't pass the class pro

Let's accept your basic premise, that it provides a meaningfully strong positive filter. We only get better software if the people who don't pass the class proceed to not write software, as opposed to writing software anyway without the training available in the following courses (and presumably writing worse software) or being replaced in industry by others who could not have passed that filter. If neither of those happens then we presumably will have better software. We will also have less software. It's not clear whether that trade-off is the right one.