Any clash of ideas could have any number of purposes, and of all the garden variety reasons to engage in one, this must be one of the lesser ones.
Anecdotally I would rank the commonality of reasons to debate as:
1- Getting something out of it
2- Sharpening your teeth to achieve #1 later
3- Escalating a situation
4- For the kicks of it. (some personalities just love it)
To find out the truth you have much better options than getting into conversation with an adversarial position.