I am equally amazed when such advice is predicated on small statistical advantages. Specifically, looking down on a greataxe vs. greatsword or taking a rapier (shudder) instead of shortsword when the avoided choice might be more appropriate flavor.
Man, those have been going since 3.0. Think about it, the ed that brought you CoDzilla has probably seen more controversy over the averaged-damage disparity among Great Axe, Greatsword, and Falchion - and even more about the Katana vs Bastard Sword!
IMHO, it's the susceptibility to simple math. You can't calculate exactly how much better the Tier 1 character really is in a succinct, precise, nearly-indisputable, statistic. You can calculate that Greatsword is 0.5 damage strictly superior to the Great Axe.
I am hoping that we are seeing a selection bias here...that the more maximizing player is simply over represented in the online environment.
Oh, definitely.
I hate to think of starry eyed kids in their first or second campaign all lined up with paladins wielding rapiers!
Don't get too many of those, college-age seems more the norm for brand-new players than the middle-schoolers it stereotypically was in the fad years. The youngest players I see at tables when I'm running intro-to-D&D games are usually there with a parent who played D&D back in the day (or maybe continuously, if you count PF). Some rolling their eyes and going along with it, some knowing all the tricks having gamed pretty much since they could talk...
...which can be kinda trippy.
I also wonder if this sort of advice we see is predicated on game store groups with adversarial underpinnings, but that is wild conjecture.
Attitudes aren't to adversarial at my FLGS. Maybe that's more the M:tG side?
Next up for me is a strength rogue (dwarf) that grapples and stabs with a shortsword...
I'd love to tell you the dwarf rogue at my table did fine...
...but I failed my bluff check.