What he is describing is just RTFM. It shouldn't be groundbreaking or really up for debate yet here we are. Manuals are written expressly for this purpose. A properly written manual has everything you need to know to get it working in a practical sense. Theory is a different matter altogether. But we are talking about engineering not science. Engineering is very much in realm of practical application.
If reading a manual front to back for a bit of tech doesn't tell you everything you need to know to use it properly then its not a good manual.
This applies well for some manuals and poorly for others. When technology changes fast you're likely to read a lot of deprecated stuff. It's an unfortunate state of affairs we find ourselves in.
I think it is my fault, I misunderstood that the GP meant RTFM where available essentially. Though I think it's still relevant, as what is clear to me now is that a lot of us are working with tech that has no true manual, just reference docs, which is a poor substitute for a real user manual.
My argument was essentially that you gain very little from memorizing reference docs. Reading a good manual is definitely invaluable on the other hand.
If reading a manual front to back for a bit of tech doesn't tell you everything you need to know to use it properly then its not a good manual.