I think the processes is more important than the goal of owning 100 things. Whittling down your stuff to 100 things could get stressful if you let it turn into a competition or you’re too concerned about hitting the number. Owning 100 things is an interesting exercise that most people living in prosperous economies don’t want to follow. But ultimately, the idea is more important than the number because striving to own less works as a check against consumerist urges. So it’s the philosophy, not an arbitrary limit of 100, that’s valuable. Think about it as owning a smaller lawn instead of worrying about how many blades of grass there are.
Is there a precedent for owning less? Probably. Since at least 1974, anthropology has suggested that many hunter gather societies were the original affluent societies. Sharing and co-operation enabled their cultures to flourish. For example, if you worked hard making a canoe, fished successfully, and then shared your catch with your tribe mates, you could relax for a few days doing cultural things, like storytelling, while others did the fishing.
Once our consumer civilization arrived, status based on accumulating stuff started picking up speed. We’re often burdened by stuff that needs carrying, storing, and protecting. Our ancient ancestors didn’t share our concept of valuing surpluses they didn’t need at the moment. They’d get what they needed when they needed it, if they could, and then enjoy it until it was time to get some more. It’d be called a “poverty mentality” in our affluent society.
Somewhere between a poverty mentality and an excessive accumulation mentality lies a sweet spot that lets us have more by having less. Putting a number like 100 on it is just arbitrary and fun but the process is what’s important.