A lot of music teachers are like that. I personally consider it shitty. My friend's first violin teacher (when she was 10 years old) made her do empty string bowing for a year. Just pull and push bowing. Now, don't get me wrong, technique is extremely important, and a lot of teachers have "if you can't do it well, don't do it" mentality. But really these people miss music is also tons of fucking fun. For a 10 year old infant, you really need a better curriculum to motivate her than just perfecting empty bowing.
I tell people: you wanna play Rachmaninoff's Piano Concerto? Go fucking play it. I mean you're not gonna play it well, even some world-class pianists can't, but if it gives you pleasure to try, and motivates you to play piano, that's fine. If you're gonna be a professional pianist, or you're a student at university, it's an entirely different matter. Some people are just hobbyists, or they want to be composers and learn piano to help compose (which is an extremely important core skill for a composer). Those people can just sit down and play whatever they want, along with things that are at their level that they can perfectly play.
I give the Moonlight Sonata credit for me becoming a decent pianist. It was above my level when I was a kid, but I wanted to learn it, and my teacher encouraged that. With enough practice on a piece that was so far above my current ability, I seriously leveled up as a pianist.
My teacher's ability to help me learn what I wanted to learn made me so invested in piano as a kid. Many kids don't stick with music because (IMO) they can't find a way to enjoy it or be invested in it. For me, what I enjoyed happened to be Beethoven, but at other times I just wanted to improvise various modern songs. (Which can be as simple or as complex as you want, but a lot of classically trained teachers can't/won't/don't teach improvisation.)
Technique and theory only get you so far. Being able to emotionally invest in your playing is what sets musicians apart, imo. And as you're growing as a musician (even when you're a kid), you're going to sound like shit if you just try to monotonously follow the instructions. I'm not sure enough music teachers get the importance of being personally and emotionally invested in the moment as you're playing. (One-buttock playing is a good word for this: https://youtu.be/r9LCwI5iErE)
The choice of what you want to play is pretty important in keeping you invested.
This hits the nail. I agree that there are tons of music teachers, especially classically trained teachers who are like this. They can't/won't/don't teach improvising, composing, encourage you to develop your personal style, ask you to bring your favorite pieces to play, teach you musicianship etc... My own violin teacher taught me nothing other than playing Bach et al. I did pass all those ABRSM violin exams, so people would call me a "good" violinist but I had absolutely zero idea when it comes to ear training, interval training, composing, improvising, listening to music, rhythmic training, notation, music theory etc. Nothing. Now as an adult, I'm composing, writing my own pieces I like that other musicians play, and I'm only now realizing how incredibly shitty my music education was. They made me a robot. I didn't learn any music, I just learned how to correctly move the bow.
This happened to my sister. She was having fun playing Disney and ABBA songs, then changed to a different teacher who discouraged her from playing anything but classical. She quit playing within a year and now refuses even to play her favourites.
I tell people: you wanna play Rachmaninoff's Piano Concerto? Go fucking play it. I mean you're not gonna play it well, even some world-class pianists can't, but if it gives you pleasure to try, and motivates you to play piano, that's fine. If you're gonna be a professional pianist, or you're a student at university, it's an entirely different matter. Some people are just hobbyists, or they want to be composers and learn piano to help compose (which is an extremely important core skill for a composer). Those people can just sit down and play whatever they want, along with things that are at their level that they can perfectly play.