Currently, segments allow the user to filter actions based on their URLs. However, for some use cases we’d like to filter actions (or rather, visits) based on “did the visitor visit a specific URL during the visit”.
For example, how many visitors did something during the visit (eg. visit url1) but did not do something else during the visit (eg. visit url2).
One workaround is to use goals for such reporting and use the goal id in segment filters. However, goals must be created beforehand and they do not allow adhoc reporting.