Those frameworks were created because those specific instances of common sense were exceedingly rare but still important. They were condensed into short lessons so people could read them, think for themselves about gains and loses, and adapt them to where they are needed.
The fact that leadership often can't do any of those 3 things right created an industry of fraudulent education teaching bureaucratic procedures. But that doesn't take anything from the original movements.
And just like programming or playing a piano, you can spend years of doing it and learn nothing because you were doing it wrong.
There are people who apply design patterns without really understanding them and there are people who apply planning methodologies without understanding them. I'd say that it's more common than not.
Every single course I have ever seen on this stuff treats humans as black box cogs that perfectly do anything you define in a ticket, even when you do a terrible job defining something. That's not teaching management to plan, that's teaching management a board game.
Meanwhile my CS class on agile and project management was just managing a real, large, somewhat purposely overwhelming project so we could stress the system and deal with failures. It showed us the value that some structure could bring, and also how you often clearly need to step back from that structure to do actual work.
I think you just had a good teacher.
Second, we can think about these methodologies as duplo blocks, and smaller practices in concert as lego blocks. You're welcome to make more bespoke blocks, but iterating from first principles every time is just not necessary when we can rely on the common wisdom gained by using more common toolkits. First principles thinking is expensive and doesn't scale.
The problem is that there is a cottage industry of companies, consultants and individual contributors trying to sell those ideas to everyone else, but common sense doesn't really pay the bills. So they must package "Agile" or "Design Thinking" or whatever into something that actually costs a lot of money and makes them feel important and authoritative.
"Individuals and interactions over processes and tools" doesn’t pay and actually saves money, so things like Agile naturally get lost in the translation.
It's difficult for leaders of legacy-built organizations to create space for common sense thinking, and when they see a room full of their employees creating and collaborating in new ways, then they pay to have you come back because for whatever reason they didn't have the time, skill or capacity to make their teams act more creatively and collaboratively on their own. Rarely is it transformative. Sometimes it's completely useless (especially when packaged into buzzword-y platitudes). Most of the time it's somewhere in-between just like any other process/culture/change improvement from leadership.
These leaders hire these companies and consultants because they were resting on their laurels instead of actively building culture while the legacy org was doing fine. Then comes a crisis or paradigm shifting moment and there is no recourse.
With visionary leadership and proactive management toward better culture and talent (which is hard to do consistently), said "cottage industry" would be much smaller.
Now there is a class of people (framework industrial complex) that do not care about real solutions but see an opportunity to scale themselves leveraging frameworks to push them to unsuspecting victims, uncaring managers and their teams. As long as universal applicability and scale expands faster than bad press in places decision makers frequent the bubble expands and money is made.