id say the primary reason for the decline of what.cd downloads was their draconian ratio restrictions, meaning that as a new account (or even old, if you weren't able to take advantage of free leech from times past, which quickly dried up into "neutral leech" without granting ratio) it was almost impossible to actually use the site.

What.cd's ratio model was zero sum, so in order for you to get ratio, somebody else has to lose it. In Economic terms that means the entire "ratio economy" freezes up and its very hard to do much of anything.

It was a continual, deep flaw with the site that admins refused to acknowledge, i hope any successors keep it in mind.

Getting punished for actually using the site and seeding makes no sense whatsoever.