Issues with AsyncIO and advocacy for Gevent instead

Gevent seems pretty straightforward. Check out this example:

Here is a tutorial.

Unlike asyncio, with gevent you can continue to use the libraries you're familiar with, and the exact same codebase can be run with or without gevent "enabled". You don't need special async versions of each library, as you do with async/await code.

What are the issues you ran in to while using gevent, that asyncio solved?

Why did AsyncIO take off when we already had gevent?