Do you like the game your playing?
So much that you'd never play another game ever again?
What if every time you sat down to play a new game, you turned it into exactly the same game you always play - how would you ever discover something new?
By the way if your first thought is that you can sit in a white room, and do some math and magically know how something is going to work, then you lack a little thing people in the know like to call experience with life.
The fact is, cooperative and competitive games are not played in a vacuum. Certain things which look bad on paper, may in the course of play, turn out to be awesome, and certain things which look awesome may be clunky.
But if you don't sit down and, you know, actually play a game RAW (that's rules as written), without changing 1000 different rules to the 'way you think things should be', then you will never be playing anything other than the game you are currently playing.
A blog is pretty big on opinion, but you can ask yourself why MMO's or RPG's have betas - or why people playtest games, and how they change in development before they are published. Trust me, if the companies didn't have to spend money on testing and development- they wouldn't. The money spent on testing and development insures a higher profit after release. Because it makes the games better (more fun, more equal, etc.) upon release.
I have played a great many games "rules as written" and find it difficult to think of one that is *just* a collection of house rules. As in, my experiences of playing Hackmaster, are as different as my experiences of playing 4th edition, are as different as my experiences of playing second edition, as they are of playing Shadowrun as they are of 3.0/3.5/Pathfinder. These are just a fraction of the RPG's I've played.
Having actually played the DCC RPG I can say that the 'funnel system' of character creation is unlike all of those other different games listed above. It is, in combination with many of the new rules, and the new dice, one of the things that truly makes DCC RPG its own game.
I challenge anyone out there to point us to a system that they've played that is nothing *but* a series of house rules to an existing system. I can think of one example - Pathfinder is a series of house rules for 3.5. I heartily approve of the reason behind those changes, and therefore play pathfinder over 3.5 - any others?