Earlier quoted context omitted.
Vegetables can release a lot of water. The amount and how much it affects the other ingredients varies significantly on which you put in, in what order, how much, and in what size of pan. If the pan is crowded, has high walls, or a lid, that can also affect how much water stays in the pan. I can't think of any situation where I would want more than a literal tablespoon of oil for cooking the first veggies thrown in (…
The first step in carmelization is to remove most of that water so the onions can reach maillard reaction temps. Try doing it without oil and an equivalent amount of water instead. It's much more temperamental.
Where did I say it wasn't?
Anyway, about adding water, I respectfully disagree. The oil is necessary and it really is a tablespoon in a shallow and uncrowded pan with the lid off.
EDIT: I'm specifically talking about browning some onions when called for as an initial step in a recipe, not for making a huge batch of them for use as a condiment. Cutting the onion into finer pieces also speeds things up.