Do you need a publisher? Or, its corollary, can you self-publish a game on your own?
The answer to this basically comes down to understanding what a publisher actually is, and what are your knowledge and capabilities to handle that.
Let's explore this through a thread!
Let's first debunk a still persisting misconception: a good game, no matter how good it is or how much effort you put in it, will not talk by itself.
It maybe was true 10 years ago (and even then), or for 0.001% of games, but let's be honest, there's only one Notch per decade.
A project is never bigger than the people behind it.
If you can't market a game or don't know (or don't want to know) what it takes, don't expect the game to do it for you.
Now we can talk about actual publishing!
IMO none of what follows can be overlooked in a 2020 context.