But obscuring may take away time from securing and it adds complexity to the system but systems with less complexity are easier to secure. So you at least have to be careful.
That's because you're looking at the order entirely wrong - you secure then obscure.
There is no such thing as "Security through unnecessary complexity", only the opposite.
The examples about changing port numbers are great, they are simple configuration changes, when people start wanting to add obscurity "features" they often wander down the path of complexity, inevitably adding vulnerabilities.
pillage THEN burn