For every user asking questions and facing issues for such-or-such firmware or software support they need in their projects, that same user would have appeared regardless if their Pi came from RP directly or through a reseller.

Every board sold would have been an extra user, the reseller isn't adding full users (although they may increase the indirect customer base!), so even gaining a user through a reseller increases the amortization divider for the support burden.

Now lets consider RAM chip support burden, the original Pi RAM chips can have issues generating support burden, and so can the reseller RAM chips. Unless RP foundation refuses to upstream link training / RAM bringup patches from resellers, there is no real additional support burden.

In fact if RP were a little more creative, they could have tried contacting the resellers to explain they can continue their modding business as long as they advertise it clearly as modified, and to inform them they will be receiving units that didn't pass the RAM tests from the automated lines, since they're going to desolder the chips anyway, this can save costs for RP foundation.