This is, I suppose, off-topic from the main premise of the article.

I've never heard of Crazyhouse before, but the drop rule is clearly inspired by Shogi (sometimes colloquially referred to in English as "Japanese Chess"). Shogi is very good. I find it to be much more enjoyable than Chess. I would suggest giving it a try if you prefer Crazyhouse to normal Chess.

Bughouse came before Crazyhouse.

In Shogi the pieces are flat, and you can turn them over to change color. That doesn't work with chess pieces.

Bughouse does work, and has been played at chess clubs for fun for a very long time.

When Internet chess came along people realized that a single board version was now an option.

It may well be Shogi inspired but then it must have happened a long time ago.