What happened to the days when you just had to implement a simple website for 1 browser, without having to worry about multiple browsers, supporting iPhone, iPad, Android, and enabling Facebook/Twitter/OpenID logins, and finding friends through facebook/twitter/gmail?
Do you really yearn for those days? Think about what you can build now vs. what you could build then.
I could build the next Mint w/o people saying "How is that different from Mint?". I could build Twitter w/o people saying That's like Twitter! I could build the next Match.com w/o people saying "But everyone's in Match.com!"
How is that beneficial for anything other than your ego?
Last time I checked, if there was no internet in the year 2012 you could invent that too. I don't really see it existing as a hindrance to your potential creativity though.
Hindrance or not, it adds an extra layer of friction in the quest of getting users, getting PR, getting attention, etc since people have been used to seeing most things already. And it's not about creativity, it's about making something to get rich first.
Do you really yearn for those days? Think about what you can build now vs. what you could build then.