There ARE tribal societies with no concept of personal property.
First, cite please.
Some only have tribal property, and some have tribal and familial, but not personal.
Any of them effectively above stone-age technology?
Sure, when a community has very little, perhaps all major tools are communal. In such a situation, nobody is going to wander off with required things "just 'cause". They will take the good spear because they think that the wild boar is nearby, and when we bring that back, whoa are we all going to eat well. Everyone knows when major tools are being used, so it isn't a big deal. This is a society that probably can't afford for tools to not be in use, or lost for no good reason. And, in all likelihood, they probably have very little in the way of luxury goods.
This is entirely different from the kender, "I don't need this, but will wander off with it anyway, and never tell anyone, and will even forget that I have it." When the kender blacksmith has no hammers, the baker's supply of yeast has wandered off, and the tanner's knives are off at the bottom of a pouch across town, and the farmer's plowhorses are nowhere to be seen, work doesn't get done.
There's nothing about the kender that renders their society untennable.
See above - for complex work to be done, the tools to do it need to be present. Moreoever, kender, as depicted, have a permanent case of unmedicated ADHD, but withotu the potential for hyper-focus. They cannot sit still for long enough to do a day's labor. They cannot tolerate being bored, or waiting for things. I don't recall that actually see any kender undertaking complex craftwork for more than a day. That's a major issue.
If they happily share surplus seed corn...
But, they don't! They won't have it on hand when you need it, because they don't seem to plan anything. And if they do have it, then you'll have to go through the whole darned community to *find* it, because nobody's bothered to keep track of it. "Accounting" does not seem to be in kender nature, so having the resources needed when they are needed is not going to happen.
People put up with organized crime...
Yeah, Capone went to jail because people put up with him. Sure.
Kender are no worse, and friendly, helpful, and of good cheer....
Kender are friendly and of good cheer, yes. They are not helpful. They may desire to be helpful, but their inability to understand the wants of other people (which is well documented - not only do they know have a sense of personal property, they are *incapable* of learning that others do have such a sense, and maybe they shouldn't violate it), or what the rest of the world considers "value" means they cannot generally act in a way that helps others.
So, let us imagine that you had a kender as a roommate. Tomorrow morning, your cell phone is gone. No, he doesn't know where it is, and never saw it. Two days later, your laptop or desktop computer is gone. It has been replaced with a vase of flowers. Very pretty. He thought it would cheer you up after the loss of your cell phone!
Next week, your car is gone. But you now have a new stand mixer. Shiny, isn't it?
The day after that, there are four large dogs in your bathroom. Your roommate says he has no idea how they got there, but they sure do look hungry.
Day after that, there's a car in the driveway. It isn't yours. And the cops followed the Lojack, and are knocking on the door.
And those are just the big-ticket items. You do not have a consistent set of dishware or silverware to your name. Your shampoo cannot be expected to be the same one day to the next, and three days ago, all your underwear were replaced with shotglasses.
This is "helpful" as a kender sees it.
