One great characteristic of human beings is that they are negotiable (Arabs do not prefer to be negotiated, though they do not mind negotiating when it is in their favour to do so). Negotiating is great; why not try to convince others of your opinion, be convinced of theirs, or reach a compromise. Without negotiation, life would be black and white. Black and white was great years ago, but not for our generation (aka the generation that rarely takes no for an answer).
There are red lines to everything. 'Red lines' is a phrase used in Arabic which means lines that should not be crossed. Most of us have limits/red lines and we don't like them to be crossed. If a person was to negotiate your limits, you would most respond in a dictator-like way. And there is not reason why you should not. We usually put limits for a reason, and if our reasons are legit, they should not be negotiated.
Personally, I do not mind discussing my 'red lines', but they are not to be negotiated especially if they are personal limits.
Limits may change from time to time as a person changes and grows, but until then, they are not negotiable. You have reasons for your own limits, as does the person you are trying to negotiate with. If you are not willing to change yours, do not expect them to change theirs; it is a bound-to-fail attempt.
When people's 'red lines' clash, it will be better for them to distance themselves from each other.
These are all personal opinions, and you are free to disagree.