Oh, this literally made me laugh out loud because the logic behind it is so dang true! I mean, why can't a charizard or a blaziken cut a simple tree without being taught "cut"? I finally gave up on it and just started teaching my pokemon cut. It works alright.
That's what I call throwing every but the kitchen sink, You ever noticed how tree's are notoriously indestructible in video games I mean you crash into a street lamp in GTA and the thing drops like a birthday candle but you hit a tree and get launched 20 foot across the road. In pokemon you got these dinky little twigs covered in leaves that are completely resistant to hyper beams fire blasts and rock slides yet a simple little cut and take it out like and emo
The rocks that you have to push around with the HM Strength did reset themselves up until Pokemon Black and White, so there's nothing wrong with hoping that the "Knee high" trees stay cut in Pokemon X and Y. Or at the very least, take one in-game season to regrow.
...I sapose the one in-game season to regrow makes sence (assuming X & Y do use seson's as that would require gamefreak to make 4 different versions of each outdoor map) but I don't think the "Knee high" trees are quite Knee high anymore in the latest gen games, I think they made them bigger