Earlier quoted context omitted.
Being able to look things up, even in seconds, is not equivalent to knowing them. When someone suggests "let's do X", you cannot reply with "but that would cause Y", if Y is buried in some pdf file on your computer, or one Bing search away - how do you know you should search for Y, when there are infinite other things you could search for.
Back at university one of the first things we were told about being an a good engineer was: "You don't need to know everything, but you do need to know where to look it up". It's a statement that I agree with. There is just too much knowledge to know it all. These days there is a very real skill in knowing how to search i.e. a second order version of the above statement "you need to know where to find out how to look…
There are some really technical things ive done in the pasy that I couldn't do without a reference right now, but once I've got the reference I don't need to be reminded about low level details or edge cases or gotchas - it's all still there in my head I just need to see the road map and it will all come back to me.