Why do kitties dribble when they purr?

Dribble what? Basketballs? ;)

I think a lot of them might do it because I heard that when cats purr it increases their saliva flow, which cuts back on fur balls getting stuck in their throat. So they just kind of have some excess drool going on once in a while.

Cats drool when they purr because it is a carryover from kittenhood. The warm, happy feeling they get from being petted is like the feeling they got when nursing, so the salivary glands start working as if food is coming.

Or as this site puts it:

“Tip 61 – Drooling cats – kneading cats – Cats that drool and knead

Occasionally adult cats will drool while they are being petted, massaged or while nuzzling into fabrics. This drooling is usually accompanied with the kneading of the cat’s paws. This paw kneading action is identical to that performed by nursing kittens and it is this behaviour that the cat is reproducing involuntarily in adulthood. Those adult cats that do drool/knead, often choose sweaters, coats or other clothing reminiscent of their original suckling environments. There, the nursing kittens kneaded their paws on their mothers, to stimulate milk flow from their teats. The anticipation and smell of the milk caused the kitten to salivate and drool.

Even though the reason cats drool and knead is in response to the warmth and good feeling they’re getting off of the petter or sweater, some people find that this is a behaviour that they’d like to correct. This is difficult since it is so primal and involuntary. It would be like trying to correct a human being for salivating at a summer barbeque. If the cat drools on you, get or wear older clothing or place a dishtowel on your lap. It would be best in this situation, to keep valuable/cherished clothing items AND/OR the materials that the cat finds ‘droolable’ locked away safely.

If your cat is not a drooler/kneader as described above, then sudden drooling normally indicates a problem. The problem can range from to a chipped/cracked tooth or gum infection (the more common reasons), to poisoning or a foreign object lodged in the throat. Try gently checking your cat’s mouth and look to see if you can spot the problem. Maybe there is a splinter or foreign object you can see and easily remove it without hurting the animal. If not, then it’s time to visit the vet and diagnose the severity of the condition.”

because they’re so damn cute, and they release the excess adorable via a drool like substance.

What??? You mean my cat is not the only one to do that?? Then there is nothing special about her.

Cats brains are just many neural pathways, once any traumatic event happens, a new pathway is formed. My cat had a long episode of being abandoned and discarded, she was almost rabid in nature when she first entered into our life.
She constantly needs assurance she is not abandoned, or is there enough food-of course.
The other cat we also adopted was the select house cat amongst many, many cats, when she was thrown out of the house and was nearly killed by the other cats-jealous cats. We took the awesome looking tabby, and subsequent kittens; she was a menace to our in house cat, still is, but after much neural adjustment she has adapted, looks at her as a mom cat – so to speak and only bugs her when she is seriously bored.
Once they start developing a new neural pathway, not in your favor, it is best to kill it fast, or it will be hard to stop. For example the new thing she is now clawing at my son’s door at 4 in the morn, and she is continuing the behavior. She has to get in there and sleep with him, and will do anything till her little brain is satisfied. So, I throw her outside-we’ll see what happens.
I know this doesn’t answer your question, it was answered already. The Neural Pathways were formed with Momma. Question I have, is why my cat is kneading now more than ever as she gets older. Thank god she doesn’t drool anymore.

I find that my cats don’t tend to swallow while purring – it seems to take a special effort of a break in purring to do so (they usually actually “gulp” rather than a normal swallow). No swallowing = drooling.