I really don't think it's something that can be "solved." But a bunch of good points have been made.
#1) The list is not everything, it's just one way to start.
If someone is really frequently making demands that the list lead to free rides (do this theme and I'm guaranteed to go wild no matter how you do it) or that people write about anything and everything they didn't specifically exclude.... Well in that case, I would understand some individualized administrative notice...
I want to be clear here: I'm imagining one or a few people who seem to consistently interact in a way that makes multiple people feel not simply frustrated, but as if they had their symbolic arms twisted. Something on the order of "I said no already, please drop it" does not seem to transmit. (I don't know that any such thing is going on, nor do I care to hear all the gory details if it is.) On the other hand: there is plenty of potential for simple frustration because people have different ideas about erotica generally. I don't think we can make rules that will change that.
#2) There are issues with either dumping the list or making it mandatory. (I wouldn't recommend doing either.)
I have a list but it doesn't usually draw company in itself. Sometimes, I get a question about some specific activity, but I try to connect multiple activities on the list more in terms of plot and character. I suspect if anything, I turn people off by having put too much time into mine. I've noticed elsewhere that some people conclude very emphatically that I "think too much," perhaps meaning I'm too much bureaucracy to write around. Okay so maybe for them, that's true. Maybe they would bore me, too, heh. Although, I think it's more that my usual plot hooks have a limited following. And I do like having some general indication of what 'first comes to mind' for other people before I start batting scenes around with them. Again, the list is potentially helpful but individual views do vary.
#3) People can and do talk past each other, despite fair intentions.
People will have different ideas about what is unusual, when exactly is reasonable to ask what is preferred, and how much to test their own limits. To others' eyes, these answers may not seem consistent for the same person placed in different types of scenes.
If you're not connecting comfortably with someone or something, and you're not interested in going on (notice no assumptions here about how it's "supposed" to work out), then perhaps it's time for something else. In my opinion, people need to look at the situation themselves and make these decisions. Administration can't do it for them.