Copy and paste from your OP,  notoneofthosedays:

"I would also like to be able to block those serial buyers who continually have items go missing. 2 or more in 12 months, same as non payers."

So what you are saying is that you would like to be able to do that, but nobody else?  ?:| 

It does not matter that would not be mandatory, it would be possible to block people who were unlucky not to receive 2 items in a year. 

Anyway, eBay will never do that.  As I said if reports are made to AP, anybody who repeatedly claims their parcels are not being received may be charged by fraud.  But AP are the only ones who can establish what is going on.