This kind of content is what I come to HN for!
What's better, it's not just about disabilities. You've got kids to take care of? Here goes one spoon. You are not a native speaker and a bit slow in getting what others say? Here goes another one. A sick spouse at home? The third and the last one is gone and that's when things become interesting!
It is a much different thing than having to take care of a child, not being a native speaker, or having a sick spouse, which describe additional difficulties onto an otherwise functional human being. Spoon theory explicitly applies to the context in which fundamentally functional actions like self-care take significantly more resources than expected.
I have some concern that this is actually a dilution of the original meaning such that it removes its original usefullness to the chronically ill community, which has to deal with the stigma of being potentially severely limited with an "invisible" illness, and the spoon theory was an attempt to describe the "invisible" illness's effect on a person's life (therefore aiding in destigmatization). By diluting the original meaning, we may be contributing to the continued stigmatizing of "invisible" illnesses, as now spoon theory is changed to mean something almost opposite of its original meaning.
On the other hand, do we really want to build this wall by saying there are chronically ill people, there are healthy people and these two crowds are governed by completely different rules, have absolutely orthogonal problems and no parallels can be drawn between them to avoid the "dilution"?
Or we'd rather say that disabled people's problems are the same as healthy people's problems, just worse and affect your life in more aspects? Wouldn't that remove the stigma and help us understand each other better?
Disabled people's problems are not the same as healthy people's problems. Spoon theory was a way to describe exactly how it's not the same.
Maybe this helps to build understanding across x and y initially, but maintaining a hard and impassible empathic barrier between groups will eventually lead people to say, "Why should I care, every time I try to relate they say I'm not one of them?"
In this specific case, why is it such a bad thing to expand a metaphor for costs to build that shared empathy? Then we can all relate to each other better.
Building empathy is the skill of identifying with situations that are not one's personal situations. Arguably, "expanding" a metaphor to suit one's personal situation is the opposite of fostering empathy.
EDIT: Towards "Why should I care, every time I try to relate they say I'm not one of them?" -> The spoon theory was not explicitly to be related to. It was a way to abstract a very real problem that has been broadly minimized into a finite situation in order to explain a phenomenon that a healthy person explicitly does not need to deal with and cannot relate to. It would be similar to me explaining a technical problem with metaphor; I'm not asking for you to relate to the problem. I'm asking you to understand the problem.
As for why should you care? Because this person is in a lot of pain and is dealing with a lot of difficulties that I'm not dealing with, and in fact, upwards of 40% (more maybe) of people in my country (USA) have a chronic/incurable condition. The scale of the problem means that developing a compassionate, understanding view will greatly benefit a significant portion of people one may meet.
Do we have any reason to think that health status / disability is discrete rather than continuous?
I'm reminded of Ludwig Guttmann, who founded the Paralympic Games and revolutionised the care of people with spinal cord injuries. Prior to Guttmann, the received wisdom was that paraplegics would inevitably die within a few years from a variety of complications; the standard treatment was simply palliative. Guttmann realised that paraplegics could live long, active and meaningful lives with the right programme of physical and psychological rehabilitation. His approach was tough bordering on brutal, but it saved and transformed thousands of lives.
I worry that spoon theory nudges us back towards old attitudes to chronic illness and disability that define people in terms of their limits rather than their abilities. We can't pretend that everyone has the same opportunities and capabilities, but it doesn't help anyone to think of ability as a finite resource that is continually depleted. We all have the opportunity to develop and grow.
Spoons theory is more metaphor, trying to describe the penalty on both time, energy and capacity a disability applies to your day to day to people who have an excess of both to handle the mundane.
One problem I have is that spoons theory says, "You have 20 spoons per day, I have 5." While the end result is the same, it's more that getting dressed in the morning requires 1 spoon for me and 4 spoons for someone with a disability. Similarly, other mundane activities require four times the amount of time and energy.
Also you can borrow spoons from the next day, either by skipping sleep or just outright pushing through an activity well beyond your disability's limit. However, then you have less time and energy the next day.
It's definitely in line with normalizing deviance. Most people who can hold down a job and an independent life with a disability are operating at their limits. They have no spare spoons for emergencies or unexpected events. The people around then normalize that and then become surprised when "one small thing" blows everything out of whack for two days. That person had no more spoons to spare. They borrowed from the next day, and now their Fibro has them bedridden, the stress triggered a manic episode, etc.