As far as I remember it was so that they couldn’t use it to create their own paid version. I think the dev wanted it to be free, but found this loophole. If I find the video I’ll edit this comment and link it
Edit: i was partially wrong above. Its not for the reason I thought it was, but rather as a business strategy. Individual users keep it relevant so theyre allowed to keep it for free, while businesses have to pay for the license to avoid being sued. Businesses are its main source of revenue. Here is a video explaining it. Its not the video I remember watching, but it seems to be correct.