It's childish. I don't understand why people try to do this. The organization is called the Democratic party. It is not clever to change the name as some kind of shorthand for your own personal opinion.

> I don't understand why people try to do this.

It's not about being clever, calling your political party "The Democratic Party" is itself a rhetorical device and a brand that is cultivated by hundred million dollar ad campaigns.

If you're going to break those associations you need to call them something else while still having your reader understand what you're talking about and 'childish insults' are one way to accomplish that. Language is powerful and controlling it controls people's perceptions. Maybe a more obvious example would be the PATRIOT Act. Who would be unpatriotic enough to vote against that?

To be honest, the name dates back to at least decades ago.