The real issue is wage expectations. In 2 ways

1) For the last decade many juniors have had unreasonable salary expectations that have often still been met. Now there is an alternative that's a lot cheaper and doesn't come with an attitude.

2) It's generally agreed that for the first year or 2 in your career you aren't that useful; after that you start to add lots of value quickly. But salary expectations don't double when you go from a junior to an intermediate - maybe they go up 25%. It's clearly much better value to hire only seniors if you can find them.

I'm not saying these are right or wrong but a whole article about juniors that doesn't mention wages, and just tries to implore companies to "do the right thing", misses the point.