First off, you said it was unstable, which means there would have to be positive feedback to make it UN-stable.

Secondly, it seems to me that there is a source of negative feedback in that if people want to be able to express stronger preferences themselves, they might tolerate stronger preferences expressed from others.

Edited to Add Clarification:

We are attempting to calibrate the social cost of expressing strong preferences. The strength of preferences expressed will vary in normal encounters due to actual variance of preferences, variance in peoples' habits of how to express those preferences, and variance in details of delivery.

If you would like to be freer to express your preferences more strongly, you can dial back the social costs you personally impose on others for expressing strong preferences. If they shift up their expressed preferences in response, then either you may as well or they are being hypocritical.

Conversely, if you think others are expressing preferences rather too strongly, first back off the strength of your own expressed preferences towards the desired level and then begin imposing more social costs on strong expressions of preferences.

Either do this gradually so people hardly notice, or out in the open, negotiated. Both options seem fairly intuitive and natural to me, though of course either one will itself impose social costs. Social skills help a lot in mitigating these costs.