[quote name='GreatDoink']Its more that I like to have all my games downloadable in one area so when/if I ever need a clean reinstall of Windows, I know it will be easy to find. But I'll probably bite on this deal - for that price you can't go wrong with this game![/QUOTE]
Though "Diversify" is succinct, it doesn't explain why it's a good argument. Allow me to try the adult way.
Personally, I wish everything could be on my Steam account, but the problem is that other places, like GamersGate, offer these titles at better prices. Machinarium, for example, is/was $5 during Amanita Design's "Piracy Sale." In that case, I have to make my own backup for the game, since buyers can't re-download it after 15 days from Amanita's server. Nevertheless, I got the game for the price I wanted, and adding it to my Steam list took seconds. (Plus, people can still see that I'm playing Machiarium whenever I load it up.)
Sure, extra passwords and usernames can be a hassle, but you can always keep lists, make backups, and generally keep track of what you buy and own. In the end, more games to play for a little extra work.
You can maximize your game library if you buy titles at the best prices from the right places.