Reason #4 you don’t hire amateur wedding DJ’s, is equipment. Think about it. If you are an amateur DJ are you really going to invest in a bunch of equipment? At best this person has a nice system in his or her home and will bring this to your wedding. However most home systems are different than professional systems and won’t really work that well at a wedding.
Lets say that this person has a nice system that will work as a DJ system. They have a wireless mic and can mix between tracks. Where is the backup equipment? Is an amateur going to invest in another system in case something breaks? Probably not.
When I go to a wedding I bring two amplifiers, and two mixers. I also bring computer. It is which is what I mainly use during the wedding and reception. However, just in case it were to crash, I also bring two Iphones loaded with music that I can mix between. I am also a member of Apple music, so as long as I have phone service, I can choose any song from their 15 million plus song library.
The point is that you not only want the proper equipment but you want that equipment backed up, because things go wrong. Don’t risk having your special day cut short because of equipment problems.