It's kind of surprising that it hasn't happened already, outside of iot junk. Seems like computer OSs just got so secure that it's become impractical to deploy a widespread exploit. And everything moved to scamming instead.

The botnets will always use the biggest bang for their buck, which at the moment is seemingly IoT devices and residential IP proxies. They do still exist: https://blog.cloudflare.com/defending-the-internet-how-cloud...

You don’t need a full host compromise to send network traffic