because steam does more than that. a version of a game digitally downloaded from steam and a copy of the same game off a cd in a box look very different. the whole file structure is messed with by steam and the compression techniques they use skew code as well. Open the location of any game you D/L off steam and then look at the installation of the exact same game off a cd, you'll notice the steam copy has a bunch of extra files, is missing some files...places files in different folders and arranges the whole thing differently. steam is only the best because it's pretty much the only one out there, which is the problem. Steam promises developers marketing dollars and help stopping pirating if they make games steam dependent....and then the game get's borked the the crap steam does to try and stop pirating.
So because steam get a custom build, this makes the game automatically corrupt?
I think this is a case of "a little knowledge being dangerous" - you know some technical stuff but not enough to understand why what you're pointing out is presicely not a problem. Kinda like the folk that are pushing all that 2012 nonsense.
As for a trend of console players not having issues, I have two responses to that
1) This thread alone shows that they are
2) PCs are a consistently moving target. Just on current release there are a few dozen different CPUs, hundreds of Graphics cards, Hundreds of Motherboards, hundreds of RAM chipsets, 3 major versions of windows and umpteen different configurations of these (Different number of patches, different editions, different OEM setup, different character sets), etc, plus all the old stuff and the stuff thats going to be released in the future. It is physically impossible to fully test a game on every single PC configuration.
Compare this to consoles - there are less than a handfull of different Xbox 360 configurations, and less than a handful PS3 issues.
PC players should expect bugs because *most* computer configrations will only see the game for the first time when the game is sold to the computers owner. Whereas consoles can be tested to bits.