Because the supplement industry is, admittedly, brimful of shysters, bullshit, shady dealers, shadier dealings and poorly-crafted uber-crap bereft of tangible benefit, a whole anti-supplement subculture has grown up in response to it, as insufferable as the hogwash claims of the snake-oil salesmen peddling ineffective sugar powder against which they rail.
Their usual patter goes something like, "You don't need [insert supplement name, usually creatine] to [insert goal you're trying to achieve]."
I usually squint at these morons and ask them if English is their second language. Invariably a look of perplexment darkens their Australopithecus-like brows. It doesn't matter.
The point is that supplements are just that: supplementary. Meaning "helpful, but unnecessary". So no, you don't need [insert name of supplement, usually creatine]. But it helps. Used regularly and dosed appropriately, the well-studied, well-backed supplements (and creatine's one of those) contribute fractional improvements which accumulate over time to yield large results.
Are they necessary? No. Are they useful? Yes.
That said, it's a battle sorting the wheat from the chaff, and supps can run you quite a bill over the long haul, particularly if you shop retail or prefer to dance on the cutting edge of what may or may not be the next big thing. Which means it's not advisable to dive too deep into the supp game if money's an issue.
Let me handle it instead. Let's you and me, dear reader, go adventuring in the wonderfully non-essential world of fitness supplements together.
You do the reading. I'll be the guinea pig. Let's see what we turn up.
Well, here's a great example of what's wrong with the supplement industry.
Some context: I'm, as you might imagine, signed up to a few online fitness store mailing lists (Bulk Nutrients, for instance, and House of Supplements, to name two I quite like), one of the upshots of which is I get their specials crammed into my Inbox regularly. My hands-down favourite for specials is an outfit called Amino Z.