Oh, it very much can and IME often does; because if there's something at A that would make it easier to deal with B, C, or D and you don't hit A first, the rest will be a lot tougher.
Or, if the end goal is at D but you happen to beeline straight to it and bypass A, B, and C (where a different route would have taken you through some or all of those) then completing your mission becomes considerably easier and quicker.
Obviously. Answering these questions is what exploration is for.
"Why are we in this dungeon?" and "What do we hope to achieve?" are, I would hope, questions that were answered before the party even left town. If you're already deep in the dungeon when these questions arise, it's a little late...