I tend to agree with not usually posting a ser number, and I can't think of a
good reason to post a serial number...
Typically, a response to a serial number will suggest that the serial number be removed or disguised.Although, I have seen serial numbers that are posted occasionally, and I have searched for that serial number to help an OP verify which Apple device they were asking about. Works well if the Mac won't power on, and the poster needs help with a replacement power supply, etc. In the past, I have offered help, and used a PM to suggest that the OP post a serial number in a PM. That would be relatively safe, I think.
But,
@zoran , why do you ask about serial numbers?