Saliva dries the skin. It is not a lubricant. Just like water doesn't hydrate the skin.
I hear clients saying sometimes that it's disappointing when we need lube, or that they don't want us to use lube, or comment when we reach the bottle before penetration "you need lube?". It's a very childish response. It is not personal: I apply lube every time, and I never had a condom that broke and I don't have to take multiple days off because of an irritated vagina. It is also important to add that our natural lubrication is not always abundant and readily available, depending on hormones and other variables, it is sometimes not enough.
There's nothing better than lube.
Clinically sound response.
However, 3 decades of personal experience has proven otherwise (for me, I'm just an outlier who knows how to prep the situation).
Concur with you about the childish responses. Just have no personal experience with that is all.
* References available upon request.