I think you may be projecting others' arguments onto the parent.
I did not read it as "everything should support the UNIX IDE" as much as expressing a preference for it and that it's a red flag if you can't even use standard vanilla tools (e.g. grep) to do basic things in an ecosystem.
I think it's fair to say that you should be able to edit code in your editor of choice and not have a terrible time.
Which brings back to having a language designed for poor developer experience, given that tooling support cannot be part of the overall experience.
So if for language X, if I as language designer want to provide the same experience as Smalltalk, either I consider the interaction with IDE workflows, or I design command line tooling to go along the language (e.g. Go).
And the command line experience comes back again to the universe where it is more prevalent, POSIXy systems.
So I don't think I am making false assumption here, as one cannot have it both ways.
I did not read it as "everything should support the UNIX IDE" as much as expressing a preference for it and that it's a red flag if you can't even use standard vanilla tools (e.g. grep) to do basic things in an ecosystem.
I think it's fair to say that you should be able to edit code in your editor of choice and not have a terrible time.