Users go through a site or journey and encounter problems, their tolerance will go down. This isn’t a ‘one strike and you’re out’ kind of ordeal, but something that accumulates can ultimately cause users to go else where.
Additionally, the metrics of success we may look at such as ‘conversion’ may look healthy, but if a user gets there while encountering problems, then next time they may not consider giving you their business.
Steve Krug documents this perfectly in his book Don’t make me think.
Krug came up with the concept of The Reservoir of Goodwill. The view is that users have a limit of goodwill that can diminish through running into problems and not having their expectations managed.
The reservoir is limited, and if you treat users badly enough and exhaust it there’s a good chance that they’ll leave. But leaving isn’t the only possible negative outcome; they may just not be as eager to use your site in the future, or they may think less of your organization.