I think we may both be right in a sense. My view is based on my schooling experiences: I have dysgraphia, which made the traditional methods of K-12 education literally torturous for me. Despite a formal diagnosis and a IEP, I had to constantly fight with teachers and school administrators to get accommodations.
I went to a small school for college, and I graduated on time despite being one of the most academically rigorous institutions in the country. College was definitely a struggle for me, but I felt that the professors were on my side, and had a holistic view of student success. This experience might be different if you went to a research institution, where classes were taught by TAs.
The only reason K12 wasn't a complete disaster for me is because my parents were immensely supportive, and because I realized that a learning disability didn't make me worse than other people. I get angry every time I think back to the other kids who were in special education with me, who were treated like problems by teachers and administrators because they interfered with the K12 machinery. They internalized all of this hatred towards themselves and hated themselves because of it.
The focus on test scores, graduation rates, and college attendance in K12 education is a disaster that hurts the most vulnerable children in our school system. I listen to my friends who are teachers, and they all know who these children are, but they don't have the time or the resources to help them. Enforcing accountability through grades and test scores ensures that these students will be left behind, because their energy is better spent making sure 10 other students score 5 percentage points higher on the next standardized test.
We will never have the number of classrooms that can provide that level of support because it would explode the budget of schools. It's probably part of the answer, though.
My anecdotal experience as a once-ago student and now teacher is that significantly more consideration goes into k12 instructional practices compared to higher education.
Perhaps it's merely a matter of student expectations aligning instructor incentives: in k12, I am being held accountable for the educational progress/lack of progress in my students regardless of ability and background, but in higher education this is not the focus of accountability. Other concerns take priority - so instructional practices tend to be traditional and, consequently, are shared less frequently?