In fact, in case the meta comparisons don't speak for themselves, I'll just elaborate.
Younger metagames are going to inherently be more unstable and volatile. The top players aren't as experienced or tuned, the "lesser" players that may occasionally beat them are often far better than people give them credit for, etc. You can't compare """nobodies""" in Smash 4 to """nobodies""" in Melee. It's silly.
Mind you, upsets in Melee happen all the time. Not as much at the highest level (e.g not to Gods, but crazy stuff frequently goes down on levels below that), but this is comparing 5-6 players who've been at the very top for many, many years to a game that's only now just establishing the quality of players beyond the likes of ZeRo, Nairo, and Dabuz.
This introduces another problem with the argument - ignoring context behind losses, or ignoring the fact that Smash 4 lacks a (good) ranking system to compare to Melee that would allow us to determine equivalent upsets. I.E., it's hard to argue that Smash 4's skill ceiling is lower because Nairo gets upset frequently, because it ignores the fact that Nairo is an inconsistent player who has extremely high highs but disastrously bad low lows.
If you bring up such upsets, it's easy to bring up incredibly consistent players who typically only lose to people that're in the same skill camp. ZeRo and Dabuz are prime examples.
Basically, """nobodies""" that come up in Smash 4 and do really well (Ned and Wrath as recent examples) might just be really good players that didn't get a ton of exposure or who's previous results were largely ignored. Ned, for example, got third at Frostbite a few months ago behind Ally and Zinoto - he's hardly a "nobody".
The added factor of two stock 3 game meta definitely creates and promotes an environment of increased inconsistency too, as you're less likely to see those sudden upsets in 5-set games.A similar thing happened in Melee, where Wobbles got 2nd at Evo 2013 - an occurrence that may not have ever happened if the sets had been best of five.
That being said, outside Japan's weird meta, this game isn't especially inconsistent. There are definitely a good few high-profile upsets or major losses that happened in a specific context. E.g., Dabuz getting 9th at Pound was against Abadango and Larry Lurr, two extremely good players, one of whom was 2-0 on Dabuz at the time.
