Just in case you're actually trying to engage in good faith, though, I'll try this one more time. If I have a compiler that is less-than-100% standards compliant, I may not be able to use a few features of the standard. That means there may be a few ANSI C idioms that I can't use. Of those, the number that I would choose to use on that size of processor is very, very few. So in practice, there is no "challenge".
Why would I use very few of these features? Because on a processor that size, you're not writing a huge app. You don't use all the functions in the standard library, you don't use all the keywords, you usually don't push the language very far at all. At worst, you might have to develop one or two idioms of your own. It's... mildly annoying, rather than the big deal you're trying to make it.
That's close enough in my book. Those MCUs are tricky targets and I can certainly live for example with not being able to pass structs as return values. Or without re-entrancy. Perfectly understandable once you take into account limited IRAM space, 128 or 256 bytes, where stack, register banks and most of your temporaries and globals need to reside.