Having a philosophical debate, and seeing it through to a conclusion, takes a lot of patience. People rarely concede -- or explain why they are correct in a way you find clear and persuasive -- as quickly as you might like. This falls under "communication is hard".
Having patience yourself is not enough. Many people will start to feel a debate is repetitive, or that if you aren't starting to concede then you aren't listening. They give up.
Some other factors that lead to people giving up include: the discussion is long and they can't keep track of it anymore (and they don't reread, and they especially don't reread their own contributions); part of the debate hinges on some subtle distinction, but before understanding it they don't see the point of it, so they think you're splitting hairs; the discussion causes them to face their own lack of skill at thinking and expressing themself clearly, which makes them feel bad and become frustrated; or they are not optimistic about reaching an agreement if one does not come "naturally" (in a quick and intuitive-feeling way), so why bother spending time talking more?
Telling people about how they should have more patience, in the middle of discussions about an unrelated topic like physics, distracts from the issue at hand. It increases the number of statements but without making any progress on the issue the two people were both interested in and trying to discuss. This sort of meta-discussion makes conversations take longer, not shorter, to reach an agreement, and it brings up new topics which people aren't necessarily interested in. It also makes the conversation more personal, and can put people on the defensive (which I don't blame them for; their personal attributes are not relevant and the other guy shouldn't be making negative comments about them). As a consequence of lengthening the discussion without making on-topic progress, meta-discussion about patience reduces the success rate.
So if people haven't got enough patience and optimism to see a conversation through to a conclusion, and giving them (what they will feel is) a lecture about patience will only make things worse, then what is one to do? Only talk to people who understand-in-advance how to discuss well? Only talk to people who are so strongly interested and motivated that they will be driven to continue for years even if the amount of progress they can detect is very small?
This problem comes up if one wants to persuade people, or to have fruitful conversations. I don't know its solution. Do you?
Is this related to the comment thread in the other post?
Why not talk to them about patience as a separate topic of morality and how to think? Then conversations about stuff like physics will be easier.