In short, grammar explanations as you know them were never designed with modern learners of French in mind:

• “Pedagogical grammar can hardly [develop linguistic competence] when it is based on metalinguistic terms and concepts (i.e. grammarians' jargon). Such terms and concepts constitute an additional learning burden and remain as a separate body of knowledge that has nothing to do with the way people actually process language.” Mohammed, A.M. (1996). Informal pedagogical grammar. Iral-international Review of Applied Linguistics in Language Teaching, 34, 283-291.

• “The innate respect that language teachers have for formal grammar instruction is not shared by theorists in second-language acquisition.” “The unfamiliar grammar term is more than a new vocabulary word for most students; it is a new concept that must be related meaningfully to what the student already knows about language and about the world.” Jeffries, S. (1985). English Grammar Terminology as an Obstacle to Second Language Learning. The Modern Language Journal

• “Our results support previous findings that explicit [grammar] instruction leads to gains in some aspects of grammar tests but not gains in accuracy in either translation or free composition.” —> In other words, teaching grammar with grammar jargon makes you score better on grammar tests, but it doesn’t make you better at using the language freely. (that’s the piece of research I mentioned earlier) Macaro, E., & Masterman, L. (2006). Does intensive explicit grammar instruction make all the difference? Language Teaching Research, 10, 297 - 327.