No. Fanfiction is (pejoratively) gay and a major factor in why all modern media is poorly written.
But good fanfics do exist. The question is, how do we hold these up as exemplars, and should we?
Fanfics are perfectly fine when written for fun or as a way of practicing your writing... The only issue is when writers arrest their development at that point.
There's a reason why ficcers described some of their own works as "crackfic" and PWP (plot? what plot?). I don't object to any of these works existing, I object to movie studios not understanding what makes a good, free fanfic versus what makes a screenplay worth sinking millions of dollars into, then expecting me to pay for it.
without having to take the time to plan out your world in advance
World-building is a two-edged sword. Yes, Tolkien did it first and best (not without some errors at the edges of story, his map of Middle Earth has terrible geography) but frankly, when I sit down to read a story, do I
really want or need 200 pages of background before I start reading your actual story? Are the skills necessary for a storyteller
always consistent with a world-builder?
I think we're mistaking building your story's
setting for world-building.
Ever heard the term "low fantasy"? High fantasy, so they say, takes place in a world with no connection to ours, while low fantasy is our world plus magic, somehow. Raymond E. Feist's
Magician, by this metric, is high fantasy, a world with magic that is not Earth. Margaret St. Clair's
The Shadow People, Poul Anderson's
The Broken Sword, John Crowley's
Little, Big are all "low" fantasy, all based on our world. But all three of these books put maximum effort into their settings. You can't really mistake any scenes from one of these books for the others.
Cynics say the ancient Greeks used mythological settings to avoid libeling anyone still walking around, and that is somewhat true. As Cabell said, another reason to use the misty past is the license to embroider freely, even as your audience already knows shares the ancient world, so you can skip all that with a short prologue. Alfred Hitchcock cast big stars because once the audience sees, say, Jimmy Stewart, it builds the character background in their heads.
World-building is optional. If you can do it, and if your world impresses the hell out of people, by all means, do it. But building your setting is not optional at all, unless you're writing
Waiting For Godot.