ME and MYW are certainly designed for that reason.
But AP rates had been great for many years through many promotions. For most of those years, only those of us with APs for our whole families were using them or even knew about them.
We made enough trips per year to justify the cost of our APs and the discounts were a bonus. I knew a couple who would plan last minute weekend trips and pop down from Illinois with their APs. I think WDW made quite a bit of money on families like ours. We have APs precisely because we do spend our money at WDW not Universal.
Good AP rates and promotions like ME and MYW are not mutually exclusive. And again, the deep AP discounts were gone before ME and MYW.