I don’t think your assumption on how well I understand how the professional world works is correct.

I understand very well that signing any NDA is by no means “zero risk”, it has a definite risk attached to it. Declining it is costly in some way, but also has definite advantages.

I also understand that very rarely is the phrasing ever “this conversation will be off the record”, but rather some phrasing including the specific topics that may not be shared, like you say for example, product details. Blanket phrasings like this are always very sketchy.