I agree with @minusfractions here - it’s not like what you said was that bad, but it did come across a bit condescending to teenagers and students alike.
Whilst this may be true for some students and teenagers, it may not be true for others. Surely you remember being at school and being swamped with work, after-school activities, part-time jobs, parents telling you to do things, and just being plain tired and lazy?
Yeah, sure, because being told what to write is the same as having creative freedom. Just because students can or may be asked to do an art-related topic during school hours does not make it their art. The same way graphic designers and illustrators spend hours at work getting paid to do their art, then go home and work on their own versions of what they actually, want to do.
IDK about you, but when I was in school I didn’t have a lot of free time until the weekends, overachiever or not. We had shit to do too, around home included. Some kids in my school did more at home than their parents, so your generalisations do come off a bit “I can do it when I am a mother, so why can’t these students with loads of spare time do it?”
I’m not a mother. However, as a non-mother, nothing irritates me more than mothers who act like it’s the hardest job in the world and no one in the world could possibly have it harder. Being a mother is a tough job, but so are a lot of other things out there - including, sometimes, being a student (depending on the circumstances).
My ultimate point here is that everyone needs to make writing their priority if they want to get it done, and they need to fit it in when they are tired, busy, and can’t be bothered. It’s not just you and not just mothers or working adults who need to make writing a prority to get any done.