…Is he an idiot? Of course you can make this stuff from scratch — how else could it have been made prior to the post-World War II era?! You just need the ingredients (which is the case for everything).
And it's not as though the simpler Chinese dishes require ingredients which aren't also basic to East Asian cooking as a whole. In fact, Japanese cooking by and large requires more specialized ingredients than most Chinese cooking. (Mirin or miso, for example.)
It's the food of regions which use copious spices or local flora/fungi where the ingredients, as opposed to technique or method, are a significant impediment to outsiders attempting to prepare them.
Meat isn't an issue, due to close culinary equivalents being found all over the world — substituting chicken for turkey or vice versa requires minimum adjustment, ditto plains buffalo for beef. Seafood even more so, since it always needs these kinds of adjustments being done regularly in any given location, due seasonality, so regional adjustments are accordingly very easy.
Again, the biggest difficulty is the techniques and methods of food preparation, not the ingredients.
That's added MSG. Monosodium glutamate is a naturally occurring substance; cheese, tomatoes, and many species of fungi (most notably yeast) all have the stuff naturally.
It's also worth pointing out that MSG has no proven negative effects unless you have an allergy to it (which is very rare, so rare that most people who claim to have it actually are experiencing a psychosomatic effect rather than an allergic relation — so unless you react to it with hives or as one might bee sting, chances are that the problem is elsewhere, possibly an actual allergy to another ingredient which was misattributed to the MSG). Additionally, whether it is added at all depends on the food, even for die-hard fans of the stuff (the effect it has on flavour depends on the food — clear soup for example usually does not have any added for this reason).