I’d change it, except that I think that it’s also true.
I think that Jonathan Last is misunderstanding Matthew Yglesias’ interests, here (the short version: the latter seems to think that American cities only had one newspaper apiece in the old days, and the former is mocking the latter in response). The Yglesias ‘brand’ has always been ‘precocious youngster;’ which is easy enough to do when you’re a kid blogging from Harvard, but considerably harder when you’re a thirtysomething, fairly doctrinaire liberal who has had all the interesting bits burned away after spending several years in Establishment Left ‘journalist’ knocking-shops*. So, there’s not exactly a reason to avoid being sloppy: the occasional dumb mistake is perfect for simulating that fresh-faced look, no?
Now, I’m not saying that Yglesias deliberately got it wrong about how many American cities had multiple newspapers in the Good Old Days; I’m merely saying that he’s got no real pressing economic reason to do the necessary research.
*Look it up.