What they were wrong about was the importance of early mover advantages.
There is also a tendency to underestimate the "early mover disadvantage", if you will - if you move too early you risk ending up being little more than a detailed market study for a company that will succeed with your idea a few years later. The current wave of delivery and mobile services includes lots of ideas people were chuckling about in 2000, but now they are functioning pretty well.
I actually have a hard time coming up with an idea from the previous bubble that is not at least being tried again now with more success, or already successful.
I'm not saying someone couldn't do it, but it's not easy.
One classic mockery target is the company that was going to deliver dog food to people. (I want to say Pets.com but it seems like they were more diversified than that.) The only wrong thing about that idea was that it isn't its own company. Amazon will happily deliver you dog food, as well as all kinds of other basic staples. (They even started a new program for that lately.)
Fresh grocery delivery from local stores is probably the best example I have... it exists, we can't quite call it dead, but only in very limited areas, and is still struggling to grow. (Bear in mind that there is a strong correlation between reading HN and being in an area that has grocery delivery. :) It isn't very common.)
I'm interesting in anybody who can come up with something from 1999 that still doesn't exist at all, or has failed so utterly that nobody is trying it today.
