nsx, I can't speak for other people that choose to not sit in an unoccupied seat because there is a coat or a backpack on it. I can only tell you that that if I come up to a seat that is unoccupied, WN's open seat policy allows me to take it, regardless of what is placed on it.

Obviously, if someone is trying to put a bag overhead or anything similar, they have occupied that seat. Having someone else put a backpack down for you when you have not come up to that row clearly does not count.

And no, I do not fly currently WN with any regularity. Back in the RR1 days I was CP twice and did not see seat saving as blatant (to include aisle and window seats) as it is now; now I am 3-4 flights a year, and only when WN is the last reasonable choice.