Hosting the image on discords CDN allows you not to give out your IP address to any person that comes across the link, prevents you from getting hammered with download requests if your upload becomes popular, and allows your content to be accessed when your own machine goes to sleep or has any kind of networking interruption.

Before discord people used to self host teamspeak or some other software. One of the big things you don’t have to think about is the person you just made a joke about or beat in an online game trying to DDOS your machine, because they don’t know where you are.