Another example: if somebody asks you to do a random task (which is essential, very important, top priority), then a tiny amount of push back - e.g. sending an email asking for clarification of what is needed and why - often makes the task suddenly become unnecessary.

The broader principle is that if a request for expenditure of time/effort/money has minimal cost or risk to the requester, they are incentivized to request unlimited expenditure if it has any potential to benefit to them.

Maybe, but then I'd argue this story proves the hurdle is way too big, if it ends up people asking psychiatrists for back pain diagnosis. Instead, why not ask them to explain the need for the chair, in writing, to the HR or procurement department? But then I guess outsourcing the decision - and all the related social risks - to doctors is safer.