System Design is about trade offs. You conveniently say "expose the same structural flaws monolithic kernels do" and not mention anything about microkernels. System arch discussions are not about who "wins", but about trade offs.

> but monolithic kernels face the same problems they did in the 80s

Putting your lack of balance aside, what problems are you talking about specifically? Are you aware of how many new instructions have been added since the 80s that were designed specifically to address the shortcomings of monolithic kernels? Microkernels, even when resources were much scarcer back in the 1980s, still did not become popular.

Both designs have their use cases. Micro and mono kernels have pros and cons but for learning purposes it makes more sense to teach about monolothic kernels since all popular operating systems follow this design.

i agree that monolithic kernels are unpleasant and brittle, but unfortunately they don't actually seem to be obsolete

That's largely a political decision because of Apple's totalitarianism.