Being able to follow written instructions vs adapting on the fly? What do DMs need more of??
Yes. The answer is "yes."
Learning how to follow written instructions is the foundation of DMing, in exactly the same way that doing a bunch of mostly-pointless essays or repeatedly rehearsing the
history of science are the foundational steps for becoming a journalist or a physicist.
Just as being a journalist does not
consist of writing essays about the classic novel you read over the summer and being a physicist does not
consist of doing lab reports on known scientific observations (that you probably goofed up somewhere along the way
anyway), DMing does not
consist of restrictively adhering to written instructions.
But the skills you develop by doing these things, and the knowledge you gain via exposure to the discourse,
are part of what makes these fields happen. In a sense, you must walk before you run, and you must crawl before you walk. The
action of crawling is not particularly relevant to running. But balance, equilibrium, observation, and other skills that can develop in the gentler environment of crawling continue to be important ever after.
Adaptation is extremely important. I'll never dismiss that. But
first developing the intuitions about what is and isn't productive, what is and isn't balanced, what is and isn't reasonable...those are absolutely critical if you want to be really good at adapting on the fly. Leaping straight into adapting, without any prior experience with an effective and focused structure, is a great way to teach yourself bad lessons that are
very difficult to unlearn.