Because flagging is better than deleting...

• A duplicate is a placeholder for the next person googling an answer.
• An off-topic question points to StackOverflow, Unix & Linux, ...
• A flag for Moderator attention can still get the attention of a mod that you're being bullied not being treated like you should, ...
• ...

Because flagging is better than deleting most of the time¹...

• A duplicate is a placeholder for the next person googling an answer.
• An off-topic question points to StackOverflow, Unix & Linux, ...
• A flag for Moderator attention can still get the attention of a mod that you're being bullied not being treated like you should, ...
• ...

_{Note¹: The notable exception being off-topic questions: they should be burninated! ;-)}

Because flagging is better than deleting...

• A duplicate is a placeholder for the next person googling an answer.
• An off-topic question point to StackOverflow, Unix & Linux, ...
• Moderator attention can still get the attention of a mod that you're being bullied not being treated like you should, ...
• ...

Because flagging is better than deleting...

• A duplicate is a placeholder for the next person googling an answer.
• An off-topic question points to StackOverflow, Unix & Linux, ...
• A flag for Moderator attention can still get the attention of a mod that you're being bullied not being treated like you should, ...
• ...