Around this time of year, people who strung their Christmas lights the wrong way start wandering into hardware stores looking for what they later find out is often called a "suicide cable."
Nevermind. The reason is that you have to be cautious about the electric current flow.
This sounds same as people being able to repair their complex equipments in 70s. But today, the user manual recommends not drinking the oil.
The m2m cable makes it possible to accidentally touch exposed high voltage leads and kill yourself. It’s why wall outlets are female for safety. I think fire is a secondary risk depending on how you use. See some of the comments for the dangers.