Because you do not have to handle all exceptions in the same way.
If you catch an exception, you may / should display an error message. But you could / should have done something else. And that will depend on the type of exception you are getting.
db →
→ , ,
...
, , Exception
try {
some code
}
catch(PDOException $e)
{
echo $e->getMessage();
}
catch(XYZException $e)
{
echo $e->getMessage();
}
catch(Exception $e)
{
echo $e->getMessage();
}