And force everyone who wants to publish an extension to buy and manage a domain name? What if it expires? You're just replacing one set of problems with another.
You could make it a requirement only for people who want to attribute “made by”. If you publish a no name extension, you could skip it.
You don't need to force everyone, both an coexist in this context. I do believe a company with nearly a trillion dollars of planned expenditure can afford to buy a domain and renew it prior to expiration.