My brother often says that any argument that goes on for a sufficiently long time will devolve into arguing about definitions of words. There's a lot of truth in this, but I don't agree that it is unrewarding. If someone is open to considerations, it's the best way to challenge beliefs, as it hits the fundamentals directly and forces to reassess the base assumptions a belief is based on.
In turn, this allows to spot and correct any potential mistakes and generalizations that the conclusion is derived from, rather than attempting to change a conclusion based on stubborn but potentially incorrect assumptions and beliefs.
It's like people from two different religions trying to argue which God is real. If they refuse to listen to each other and push their own beliefs, they won't ever come to an agreement, and both will think they are right because that's their belief, they're operating on the assumption that their position is the correct position.