#People don't necessarily want to play the Rules Committee's game
The basic idea of Commander/EDH has appeal beyond just the particular card pool. Some players want to play 100-card singleton with generals but don't share the Rules Committee's appreciation of old cards, or expensive former tournament staples, or crazy combo decks.
Of course, the Rules Committee does try to take the needs of the community as a whole into account, but they're basing their judgements on convention games, online discussions, and their own experience.
So, play groups start to come out with their own rules and restrictions — sometimes unspoken (even the RC seems to assume some level of "gentlemen's agreements") — to create the Magic-with-legends format that they most want to play.
#Multiplayer EDH isn't a very "balanced" format, really
EDH lets you play Sol Ring, man. Sol Ring!
And Hermit Druid Combo — have you seen that deck?
The EDH ban list is generally very forgiving of powerful cards, especially enablers, as long as they don't win the game outright or cause "unfun" board states (e.g. repeatedly blowing up lands). The logic is that the other players will "balance" the game by teaming up against you until they've whittled away your advantage. This is why Duel Commander has its own separate ban list.
Even in multiplayer, though, some people don't really like the "gank the guy with the cheaty card" experience (I don't). One way to fix that is to change up the banned list.
The "casual" metagame isn't like a competitive metagame
In tournament Magic, or hardcore Magic using near-tournament-quality decks, players approach deckbuilding with a competitive mindset: they build decks to take on the overall metagame. In casual Magic, it's often the other way around: players want the local "metagame" to support their favored decks.
All Magic players have their own styles and their own tastes. But "Spike-y" players tend to appreciate self-expression within the bounds of what's powerful and viable, whereas other folks don't enjoy having to choose between playing what's good and playing whatever it is they love to play.
So, let's say your casual play group really likes "tribal" creature decks. All of you want to play games of Magic where those decks can do their thing and clash against each other. The mainstream EDH rules are only designed to support that up to a point. If you start to have problems with other strategies that naturally waste the kinds of decks you actually want to play, maybe you'll start adding "house rules" to limit those.
You could see this as a reactionary flip-out by players who don't want to challenge themselves, but that's rather uncharitable. Oftentimes it's more like formalizing unspoken assumptions that have always been there, to get the group back onto the same page.