So was I lied to? Were millions of film students lied to? Not really, but I believe the tides have turned. Nowadays, it is far easier to self-produce and fund independent films. Give me $10,000 or even $5,000, and I can probably make something watchable. With such a small budget, turning a profit on my film may not be as hard as people make it.
But will it sell? Ahh. There's the rub. One has to be completely original, yet remain within the framework of some familiarity. Such as District 9. At first, it sounds like a typical alien invasion story, but the twist reveals that these aliens live in the ghetto. And humans have put them there. And the movie takes place in Africa. The familiarity of the alien invasion story draws us in, while ghetto aliens in bras and panties who abuse cat food like crack keeps us there.
The genre rules are the same though. You still have the bankable horror film, crime drama, romantic comedy, or sci-fi adventure. Indies can play around with genre constructs, especially to drive up originality factor, but too weird and you might be another Ed Wood (one can argue Plan 9 was a genre experiment).
As much as we would hate to admit, the Industry is a business. You gotta play to the masses if you want to stay on top. Of course, the most bankable thing you can do is to bring "a name" to your project. Names come at prices, but sometimes the names alone sell. For example, Tyler Perry can take a crap on a piece of paper, call it Madea Goes to the Bathroom, and will still turn a profit because of the marketability of his name. Hell, may even be #2 at the box office, right after the Halle Berry/Angelina Jolie lesbian film, also co-starring Beyoncé as the jilted lover.
Are there some films that prove marketable even while failing at these "rules"? Sure, but for most of us, we might as well throw that $5,000 off a cliff because no one will see our films. Alternatively, you could shoot the money floating gracefully towards the bottom of the abyss and call it a social commentary about the American banking loan system. Then post it on YouTube. Take that, Keyboard Cat!