You're completely correct! The absolutist position I object to is the idea that any condition on particular ways of using software, even a copyleft condition,

You're completely correct! The absolutist position I object to is the idea that any condition on particular ways of using software, even a copyleft condition, makes the rule harmful. That's clearly not the case for rules attached to the freedom to make and share changes, to build applications from libraries or frameworks, and so on. Share-alike rules about those kinds of uses can and have been prosocial in practice. They can be prosocial for dev tools, too. We see that every time developers make code open in order to get free code hosting, CI, coverage, and so on from SaaS companies.