Of course they are 'guidelines'.

If a thread is of particular value - such as a tutorial - the 'rule' will not be applied. Greater good.
Totally slack rules means everyone abuses & site becomes a pain to use.
Like life in general - common sense - initiative - value --etc, take precedence over black & white 'rules'
Overall for general screenshots it makes things a lot easier for everyone if the majority stay within the guidelines. A few of us have been otherwise engaged recently with real life stuff ... some have been missed ... no biggy ....
Simplicity is the ultimate sophistication. – Leonardo da Vinci