Since markers and any help of that kind can be turned off, i don't see the fuss. I do not agree with the idea of "It shouldn't even exist". The person next to you might want to play with markers on, why should anyone forbid him to do that?
I was mistaken about the markers, I thought they were a separate thing from the questions marks, but it's almost certain they're the same - a specific symbol replaces the question mark once you have discovered it. I fully support having the option to disable of course. Some people will just want to cruise through that stuff and tick off the numbers. Whether it amounts to filler or not remains to be seen, but with the devs saying the main story alone is 50 hours, I suppose that's not likely. I didn't mean to start a fuss over this.