To expand on this, this is not just about verbatim memorizing discrete facts - algorithms, definitions, dates, events, vocabularies, grammar rules, musical notation,... - it's about learning when and how to use or apply them.
Facts become information, information becomes knowledge. Learning is about processing what's in front of you. Becoming aware of facts presented to you in a book or a powerpoint presentation, then reflecting on those facts, turning those over, engaging with them, asking new questions, trying to apply them in different contexts and so on.
As you do that, the entire experience of gaining knowledge also leads to self reflection. That is, learning to know yourself. And others around you. When does it matter to apply what you know? When not? What is relevant to me and to those around me at which point? This is about learning to formulate effective critical argumentation based on what you know. And that involves challenging viewpoints including your own. Context matters.
The latter is a skill. It's something you need to practice if you hope to be any good at it.
Expanding on your example:
I think it's important for engineers to have a proper understanding of the details about nuts and bolts when they are actually building the Eiffel Tower. But in a meeting with stakeholders - the mayor, city officials, banks, sponsors,... - it's also about knowing that they probably don't care about those material aspects. Unless the context changes and those become super important. Like when it becomes appartent that the iron wears out because of changing weather conditions. And even at that point, those stakeholders likely aren't interested in the exact chemical formulae that explain the process unless it's necessary to cover risks and liabilities. They simply want a good, terse explanation from an expert and an assurance whether it can be solved.
Hence why knowing things isn't enough. It's about knowing how and when to apply them effectively.