The usually astute historian Julian Zelizer, writing in Dissent, manages to cram a couple major misconceptions into one sentence here:

While Howard Dean’s 50-state strategy in 2006 and 2008 resulted in more congressional Democrats emanating from conservative districts, Pelosi (unlike Senate Majority Leader Harry Reid) has not allowed this broader coalition to become a crippling barrier to legislative victory.

First, the degree to which Howard Dean's 50-state strategy contributed to Democratic successes in 2006 and 2008 is highly debatable. The notion of expanding the electoral map and trying to pick up Democratic seats in marginal Republican districts was not unique to Dean. That's what always happens to parties when they win. The main tactical argument between Dean and his critics rested on whether the party should devote its resources to the districts where it had competitive candidates -- that is, the districts where it did in fact pick up a lot of seats -- or whether it should literally spread its resources through all 50 states. You can argue that Dean's strategy was worthwhile, but at best it resulted in marginal gains over the tactics favored by other Democrats.

Second, Nancy Pelosi has done a lot of things right, but the straight comparison between her and Reid is totally unfair. Reid faces a a supermajority requirement that forces him to gain the unanimity of all 60 Democrats, a number he only had for a few months, and which includes Joe Lieberman. It's safe to say that imposing a 60% supermajority requirement upon the House would make Pelosi look far less effective. Pelosi didn't let the conservative Democrats become a barrier to legislative victory because she didn't need their votes. If Reid could pass anything with a majority vote, and could let Lieberman, Ben Nelson, Blanche Lincoln et al walk any time he wanted, he'd look like quite a hero. As it stands, pulling together 60 votes for comprehensive health care reform is the most remarkable legislative achievement of our time. The House vote, while impressive for Pelosi, pales in comparison.

There's a reason that House Speakers are so frequently described as iron-willed rulers while Senate Majority Leaders are so frequently seen as feckless. (Noam Scheiber wrote a great piece a few years ago about the recurrent GOP tendency to turn against their Senate Majority Leaders.)