Requiring a Mac reduces the number of low-effort “checkbox ports”, which the google play store has no shortage of. Nobody who just wants a quick, easy presence on iOS will buy a Mac, leaving (mostly) devs with the intent of building decent iOS apps.

Disclosure: I work for Apple but not on anything related. I think there are reasons to believe there is some dark purpose behind this, but I think there are also reasons to believe its just Apple continuing its privacy push and not wanting to see even more data go unnecessarily to the data hoarders. I'm personally super happy I can decide to not hand over my email address, I think that's a huge improvement.

Why would Apple spend the time and resources to port their development environment to other platforms?

Have you seen the few apps that Apple has ported to other platforms like iTunes?

It may not actually work as much as they would like to believe but I do think that is their thinking here, I don’t think the goal is just to gouge us for money.

An Apple developer’s license is $99, not thousands.

The point is that the developer license isn't enough, you have to buy a Mac to develop iOS apps

As others have pointed out, you need a Macbook to develop said app.

I am surprised to hear the priced decreased - back when I did that sort of development is was $150 to publish free apps

He's talking about the price of the mac, not the license