If you made this paid subscription the site would be gone within a year.
People simply wouldn't sign up here, and one of the things that MN prides itself on is that it is available to anyone 24/7. And given the numbers of posts vs the numbers of threads which are copied across in the tabloids it's not worth doing.
And as an aside, I find it interesting to note which threads end up being taken for copy. Not the general aibu or chat ones, but the more sensitive ones. Interesting that tey're always from first time posters, often who post late at night or early in the morning, usually an unusual scenario.
Given the hundreds of threads which are posted every day, many of which run into hundreds of posts and sometimes even more than one thread, does no-one find this remarkable and wonder just how many of those threads are in fact planted there by someone in order to draw attention to the site?
It's never a well known poster's sensitive thread that is taken, or one which could really get the DM frothing. Look at the "builder scammed my autistic kids" one for instance. That thread is at part 2 now and yet it was never picked up? Why not? And yet a thread from a first time poster which may be sensitive is always the one to be grabbed and reproduced.
I think that, rather than getting outraged at the DM and the like and claiming that they are putting people at risk (they're really not,) people need to think more along the lines of that the DM and their ilk have plenty of members and new joiners here who are prepared to tell a story to gather supportive posts which can be reproduced there tomorrow.
I think that the idea of someone actually being at risk from having their post copied from one site to another is far less of a likelihood than the fact that most of the threads being copied across were probably just plants anyway.