there is a conversational failure mode we can avoid by talking about X first

Not so much even a failure mode, as an observation that the optimal path is X -> Y -> Z and if you start anywhere else you'll have to come back to X soon, anyway.

some topics will cause the conversation to proceed more usefully (by addressing the fundamental issues first) and others will cause it to proceed less usefully.

Yes.

such expressions of opinion can be expected to cause a conversation to proceed less usefully.

More than that, CYP generally aims at putting a full stop to a particular branch of a conversation. It's like "This here is a Sacred Truth, all you can do is accept it, and we will tolerate no doubts about it".

In that case it really is about who is deciding what and who has the power.

Claims to power, yes, not necessarily the actual power.

the two aren't comparable.

Yes.