S'mon said:No, they're just highly simulationist game systems. But plenty of stuff that happens in Glorantha was not possible in the Runequest 2e ruleset. In the Dragon Pass game, Harek the Berserk can destroy whole legions of Lunar troops. It's impossible to create a human in the Runequest rules who can do that, AFAIK, no matter how experienced/heroic.
...yes, different game systems produce different worlds and feelings in play, even when they're supposedly based around the exact same thing. For instance, people can throw fireballs in MERP, but it's easy to conceive of a Lord of the Rings RPG based off of the exact same material where this is not the case. Likewise, the War for the Throne board game for Exalted obeys different rules than Exalted itself, despite being based on Exalted. Since they're different games, what's the problem?
More seriously, I know what I like and don't like in games. I run games where the game rules are the physics of the game world, and it seems to work pretty darn well for me. I stay away from Order of the Stick-esque silliness where metagame terms are explicitly called out in play, and the chief visible manifestations of this to my players are that I do not choose to use plots which are contradicted by the game rules - so level-20 fighters will never die from simple misadventure - and that organizations and governments are influenced by the game rules. In D&D practice, this means that actually holding the reins of power practically requires being high-level or otherwise having the backing to not get killed offhand by the first high-level jerk you tick off. As a player, I'm bothered by plots that are directly contradicted by the game rules, especially when there are countless ways to revise any such plot so that it's not rules-impossible - Overking Tarkane the Usurper could easily die of old age or meet with fatal misfortune on a dire tiger hunt or what have you, the foolish level-3 apprentice could have successfully used a Scroll of Planar Binding (on a roll of 9 or higher on a d20, no less) that belonged to his master rather than contravening the rules and casting it as a normal spell, et cetera.
I understand that there are reasons why other players might prefer a "fluff trumps crunch" stance, and that's fine. To say that it always does, however, is just plain wrong.