Oy, vey. Is there some sort of machine that goes "Bing!" every couple of days, and spawns yet another iteration of this topic?
Use a hydrometer or don't. You don't
need one, regardless of whether you're brewing AG or extract. Repeatability, monitoring of fermentation, etc. - those things just aren't important to some people. You have to decide if you're a person who likes controlling things, or if you prefer to just throw things together and let the fallout drift randomly.
Me, I like to throw things together - but then I take detailed notes of how much of what I threw in the pot. Frankly, I can't abide the science vs. art debate; brewing is at its core a combination of art and science, heavily weighted toward the latter. You want art, go make wine, where you people respect you for throwing ingredients into a pot and praying it comes out drinkable.
Do what you like; brew the beer you like. Make informed choices. Just realize that some people get cranky when you come crying about something that could have been avoided had you chosen differently. It's one thing to choose not to use a level; it's another to cry if the house falls down
because you've chosen to not use a level.
Bluntly, if you choose not to use a hydrometer, you abdicate the right to complain and/or worry when a ferment doesn't go according to plan.
Cheers,
Bob