People may use whatever license they wish, but it's important to be clear about what is (and is not) FOSS.
The term "free software" was effectively coined by RMS & The Free Software Foundation. It is used explicitly when referring to copyleft licenses, which restrict certain uses of the licensed software in order to protect user freedoms. You can argue that other people use the term in other ways, but the most commonly accepted definition is the one used by the FSF.
The term "open source" is somewhat vague. Software that is merely "open source" is not necessarily licensed in a way that allows redistribution/modification. The only thing guaranteed about "open source" software is that you can read the source.
'Open Source' was/is a rebranding of the term 'Free Software' to make it easier to sell to suits. Eric Raymond has said as much about his invention of the phrase. The idea that it's just about "being able to read the source" is wrong. It's not vague at all, you just didn't do your research.
Otherwise, I concur.
https://writing.kemitchell.com/2018/11/05/OSD-Copyleft-Regul...
https://blog.licensezero.com/2018/09/14/free-to-take-freedom...
There are heaps of disputes about whether licenses qualify. Check OSI's license-review list, or Twitter, or, frankly, HN.
OSI and FSF would disagree.
> We could rewrite any copyleft license as a limit on use.
What is the purpose of your argument? What are you trying to achieve? Do you want a Lobjan specification of FOSS? There may be difficult cases around the edges of the definition of FOSS, but restrictions on commercial use are not one of them.
As for FSF, their process for considering licenses is a black box. We have "What is Free Software?", published largely in response to the creation of the Open Source Initiative. But it's no more a technical specification than OSD is.
I never claimed that restrictions on commercial use are "open" or "free", or that any particular license that does so is "open" or "free". I have and do claim that neither OSI nor FSF provides any clear, complete guidance on what "open" or "free" copyleft can and cannot do. Consensus within the relatively small groups of folks actively engaged with those institutions is founded in good-sounding generalities, not any rigorous definition.
