Then the article goes on to just list Google and Twitter, basically... are they enough?
(disclaimer, yes i'm commercially interested in the answer to this question.)
But depending on the biz you're up against it might not be useful, i.e. you might need to keep an eye on who and how they're marketing themselves.
In fact, I generally think that a minimum of time should be spent considering your competition (at least when you are a startup). Perhaps you set aside a few hours each month to review their progress, compare it to yours, identify features or strategies you will "borrow" from them (ie "fast follower" strategy), and consider what they'll be doing in the future that you need to respond to, or get ahead of.
Then, add those items to you action plan, and forget about your competition for the next month - focus on building YOUR business instead.
Just my $0.02 from the startups I've founded, funded, and grown.