Of course it is a valid argument. You just don't like it. That's your right. But claiming the argument is invalid is just dumb.
Your OS analogy is also poor. There's about two decades worth of discussions about memory protection in AmigaOS and it's spiritual successors (AROS, MorphOS etc.) for example, and while some people involved with those are strongly in favour of adding things like memory protection (though it is hard to do without severely breaking compatibility), there are also a lot of people for whom part of the appeal with these OS's still is that a user can hook into anything and everything:
For AmigaOS there are user-level applications that can replace the task (process) scheduler, for example. There are user-level applications adding virtual memory. There's a library that gives any user-level application free reign to more easily manipulate the MMU. There OS itself provides API calls to allow user applications to replace the code used for ever library call (system wide - the equivalent of being able to override syscalls in Linux...). There are assemblers with explicit support to muck around with hardware registeres and OS structures. There are applications designed to trace everything that happens at the OS level. And a lot of these capabilities are in fairly common use by the (admittedly few) users of these systems.
You might argue (and I'd agree with you) that this isn't a great basis for a modern OS. But that does not make it an invalid stance - most of these people don't want what we consider a modern OS. Many of them instead want something where they can do exactly those kind of things with nothing like a userland-kernel barrier to deal with etc.
Your OS analogy is also poor. There's about two decades worth of discussions about memory protection in AmigaOS and it's spiritual successors (AROS, MorphOS etc.) for example, and while some people involved with those are strongly in favour of adding things like memory protection (though it is hard to do without severely breaking compatibility), there are also a lot of people for whom part of the appeal with these OS's still is that a user can hook into anything and everything:
For AmigaOS there are user-level applications that can replace the task (process) scheduler, for example. There are user-level applications adding virtual memory. There's a library that gives any user-level application free reign to more easily manipulate the MMU. There OS itself provides API calls to allow user applications to replace the code used for ever library call (system wide - the equivalent of being able to override syscalls in Linux...). There are assemblers with explicit support to muck around with hardware registeres and OS structures. There are applications designed to trace everything that happens at the OS level. And a lot of these capabilities are in fairly common use by the (admittedly few) users of these systems.
You might argue (and I'd agree with you) that this isn't a great basis for a modern OS. But that does not make it an invalid stance - most of these people don't want what we consider a modern OS. Many of them instead want something where they can do exactly those kind of things with nothing like a userland-kernel barrier to deal with etc.