[devwastaken]

Theft. That's the reason. People could upload others mods to be paid. Or they would use assets they were not allowed to sell. The cost of litigating this is far too high, therefore a system that allows the theft cannot be regulated civilly. Meaning the system should not exist.

Mods work better in an open and free environment that lacks monetary incentives.

[xeromal]

We can't figure out how to protect content creators so they should just do work for free seems like a cop out to me.

[BlueDingo]

Or maybe they know the cost and it isn't worth it to them? The poster you respond to mentions litigation. That's how IP theft is handled. How much legal fees does anyone want to incur for due diligence or litigation or defense for mods and plug-ins. Only the top few will earn enough to justify the effort. Everything under that will be left to fester. Quality free and low cost mods will get copied and promoted to scam money and the people working hard, that you and I both wish to help and support, would get no help or compensation.