They aren't refusing; there is an unlimited duration now as long as you keep paying.
> AppleCare+ for Mac extends your coverage from your AppleCare+ purchase date and adds up to two incidents of accidental damage protection every 12 months
After 2 or 3 years [0] (the initial duration depends on whether it is AppleCare or AppleCare+), you can pay more and get an additional coverage [1]:
> Your plan coverage may continue beyond 24 or 36 months, on a monthly or annual basis, until canceled.
[0]: Before adding AppleCare+ to your cart, the ad copy says "Get up to 3 years of accidental damage protection and expert technical support from Apple."