Plural partitive?

Other articles in this course describe des as a partitive e.g. Du/de la/de l'/des all become de/d' in negative sentences (French Partitive Articles) , or describe des as a partitive article. I think that using "uncountable" as the definition sends us on the wrong track. I think that saying partitive singular is for when the number is not relevant, or not inferred, rather than uncountable e.g. "some tea". Partitive plural is for when there is clearly more than one of the object referred to e.g "some teas". For example: Did you try some tea? Singular partitive, uncountable (or more exactly, counting is a meaningless concept in the context) Essayez vous du the? Did you try some teas? i.e. different types of tea, and you could count the number of teas you tried. Essayez vous des thes?

Avez vous essaye du the? Avez vous essaye des thes? :(

On the contrary, I believe the difference between uncountable (or mass) nouns vs count nouns is key here. The former use the partitive article, the latter the indefinite article, which can be singular or plural. Both types of nouns, of course, use the definite article. All examples I've seen so far with "des", including in the lesson you refer to, could interpret "des" as the plural indefinite article, rather than the "plural partitive" article. Which is why I wonder if the latter concept actually exists at all. Even in your example with "des thés", it's very clear that we're talking about TYPES of tea, or different tea flavors, rather than an indefinite amount of the liquid tea. I'll be happy to be proven wrong if someone can come up with a good example of the plural partitive.