With the exception of word lists for foreign language study (and to be honest, vocabulary is rarely my most important issue with foreign languages), I haven't found anything that benefits from studying flashcards.

I know that flashcards were a big thing among students when I was in grade school and college (decades ago). I'm sure they helped students memorize pieces of information, but I'm not sure they helped students understand them.

Thing is, current flashcard software (including Anki) does not support complex "study and understand" workflows very well, but a lot could be done to improve it. Even something as trivial as supporting explicit dependencies among cards, i.e. "don't bother to show card X unless you have managed to push out repetitions of cards Y and Z beyond $time_interval" would help a lot.

This would also enable flashcard/SRS workflows to interoperate seamlessly with other memorization techniques, like memory palaces or mind maps. Foreign language vocabulary is the rare example of a domain that doesn't need these things, so flashcards are perceived as "good enough" for it.

OK, thanks for confirming that it's not just me and that Anki and friends are a study tool with very limited usefulness.

mostly in schools there's no understanding whatsoever: to the contrary, students have to REMEMBER what the teacher provided as a valid understanding.

Fortunately, no, not necessarily: not in the schools I have been to. In the schools of my youth, you had to understand the taught, not just remember it. Students were evaluated for how well they had processed the information, for their mastery in its "handling".