One of my favorite websites is having a short story contest in which reader votes play an important part in who wins.
There will be 20 winners and there are at least 700 entries. Two of the winners get $15,000 each, are included in a published anthology, and have an animated short made based on their story. Six more winners get $5,000 each and are also included in the anthology. The remaining twelve winners get $3,000 each and are included in the anthology. In all, there are $96,000 of prizes to be awarded and the recognition puts the winners on their way to a career of story telling.
Reader voting isn't random, however. As elusive and seemingly subjective as it may seem, "quality" as Robert Pirsig described it in his signature novels, "Zen and the Art of Motorcycle Maintenance" and "Lila", is still something real, even if it may be intersubjective, rather than objective. And, it is much easier to recognize it, than to create it.
The best stories tread a fine line.
On one hand, they can't be stale and cliched. It has to be fresh, with some elements that are novel or unexpected. Also, the execution and delivery have to.be good from a technical mastery perspective.
On the other hand, a story has to tread close enough to established tropes that the audience has some sense of where the story is likely to go and finds some elements of the story comfortably familiar. To say that there are true "universals" may go to far, but there are characters, settings, situations, and plot devices that are proven winners if done well, and a story teller's job is to assemble a good mix of them in a competent manner the works.
Yet, a story teller doesn't have to adhere to any particular stylistic convention (even within genre writing there is room to develop a distinctive take on the genre or a sub-genre), the style just needs to be distinctive. The creative arts reward someone who has an identifiable style and trademark, not a jack of all trades who is competent is a wide variety of styles and genres. Maybe, if you are very, very accomplished, you can branch into two or three different styles that have overlapping aspects to them.