The issue with that is trolls who either 1. ask for source when something is an easy to find fact of life (i.e. it doesn't need a scientific paper / article or whatever to prove). To later try to convince / discredit you that your link does not show what you claim (when it does). This one is to waste the other person's time and nothing else, and is really popular by kremlin bots 2. launch an outlandish claim with no source, you counter it and then you are asked by OP to provide your source, then back to 1. for the rest of the bullshit that they do.
Ultimately it doesn't matter much when you reply to 2 - 3 people like that, but posting more often, it does simply waste your time.