All I can tell you is that it is not optimal design practice and you have no way of really tracking the failure rate. I can tell you is that sagging power lines is not optimal design practice. What you say about the X6800 is true, but still not optimal practice. This is a problem we never had before a ton of channels were added, which is why there are so many vintage two channel receivers are in good working order.
So, as in all things you have to put cost in your design equation. However, not having power sag per channel as you increase power, is optimal design practice which is undeniable. I won't deny that eliminating the problem is very costly and difficult to design into a domestic living situation.