This element of finality is the way in which they resemble the basic method D&D uses to resolve combat. Instead of the GM deciding when the situation is resolved, a mechanical process is used to do this.I think the reason that SC's work for some and don't work for others is because they are the solution to a problem/desire only experienced by some groups. The main problem/desire they seem to solve is the need for a pre-determined & closed point of success to a series of skill checks used to obtain a goal. Outside of you need X successes before Y failures they don't really bring anything else to the table that can't be provided by a DM calling for skill checks and letting the fiction flow from what the resolution is organically.
It seems the want and/or need for this is driven primarily by having a DM/group who is not able to bring a series of checks to address obstacles to an organic length & resolution (based on the resulting fiction) that is agreeable to the group without some kind of hard delimiter