This is not impressive.
If I go to the member center, I enter my credentials, do a team selection, and I am in.
I can then click into forums, and I am logged in. But I have to enter through the side door.
If I go directly to forums, and click log-in from there, my credentials login always fails.
The message I see (which I pasted below, but does not appear) is
"This Apple ID cannot be used for this service. Please create a new Apple ID"
Can we go back to the previous system? This feels like a retrograde step.
Better still, can we have an Apple centric version of Stack Overflow? If Apple developers can provide assistance to each other, it would be good. There are web-based solutions to do that sort of thing.