User experience online is very similar to the user experience you get when going to a grocery store. You want a pleasant time without any hassle. You want to be able to navigate the store quickly, get what you need right away, head to the checkout line without a wait, and get back home.
You don’t want to deal with a slow cashier, items not where they should be or out of stock, hostile employees, or a crammed parking lot. You simply want what you came for (groceries) and be on your way.