This is a bit anecdotal, but my freshman high school programming course, in 1999, was taught in Dr Scheme. I had already been programming in Q Basic and C++ at that point, and found it _maddening_. Not because of the perens really, editor was fine, but because of the lack of structured constructs for control flow that I was used to. Tail recursion, while now quite natural to me, just did not make sense at the time. My classmates had less trouble getting that bit because they had no preconceived notion of how control flow worked I think, and also didn’t expect parts of the language to exist that either didn’t or were hidden in the teaching mode we had to use it in. For most of a decade I listed that as my least favorite language of all time, until going back to find out that many of the things that were missing were actually there, they had just been hidden from us, pretty sure by imposing the “beginning student” mode:
https://docs.racket-lang.org/drracket/htdp-langs.htmlSimplifying for teaching is good. Making useful things completely unavailable… not sure I agree.