this game may have all the trapping of open world games, like tons of quest and icons and collectibles in the map that distract you from the main quest. but the combat really make those flaws irrelevant for me.
the sidequests didn't do anything different than other open world game where it's basically go to point A and fight enemy B etc, but while I got really bored at the smaller sidequest in Witcher 3 for example to the point of intentionally avoid activating the quest altogether. here in Horizon, I'm eager to do those quest and errand, because the combat make it satisfying enough that it's more than just a distraction from the main quest. finishing a sidequest in Horizon could mean a really epic showdown with multiple robots where you barely survived.
also, the map is not too big and dense enough that I don't feel the need to use a mount to go anywhere. there's always a pack of robots or crafting items or collectibles or errands etc along the way that you never feel like you're just walking mindlessly in between quest marker. compare this to FF XV, another open world game that I like, but I could never go anywhere without using car fast travel or chocobo, because the map is so big, your running speed is simply not fast enough to go everywhere on foot without feeling like you're wasting your time.