This person is speaking from the employer's perspective, I struggle to see how becoming a parent would change the equation for their side.

They want to hire people who already have some degree of relevant experience. That is a reasonable requirement. If that excludes some parents who don't have time, so be it. Being a parent is one of many lifestyle choices that can limit one's ability to arrive at an interview with sufficient background knowledge. It does not warrant special treatment & exception just because it's parenting.

One of the very real sacrifices of becoming a parent is that your ability to just try out new stuff be it a job or a hobby becomes very limited.

It's not possible to have it all in life. The choice of having kids (and being a good and responsible parent to them) obviously closes some other doors.

Should number of kids come up in a job interview?