In Software development scenario specify how system will be used. Scenarios are written in plain language so that whole team (business, technical,marketing) has same understanding.
To justify a scenario you need to provide data on current problems or future benefits:
Data about past problem e.g. User has to spend 1 minute to register
Data about future benfit e.g. User will be able to register with 2 click.
Here is example scenario:
abc.com website Webmaster Alan wants to know how many users are visiting website, what page is visited, how much time user spent. Alan will drill into country, city from where user is visiting. Using this report webmaster can determine impact of advertisement done in local newspaper. The data will also help in determining area of improvement and where website need to be advertised more.
Based on this scenario, company can get logs from website server. Build report of user. Add more details about user IP and then get this data joined with marketing campaign done in local newspaper.
After building this scenario if company determine that no user visited abc.com (or very less user visited abc.com) - the effort of getting IP, country , city level data and joining with marketing campaign go waste.
Instead of flying blind abc.com would have implemented the scenario in phases.