More Q&A - Why No Generic Attributes?

Question from Wes Haggard:

A while back I posted https://weblogs.asp.net/whaggard/archive/2004/10/12/241476.aspx about having a generic type inherit from Attribute. Do you know why this is prohibited in C#?

My attempted response:

I used to think it wasa a CLI restriction, but now I've scoured the docs and can't find anything like that.  So, you'll have to settle for a big fat "I don't know".