Lotsa folks do, but I ain't one of 'em. 32-35mm tires and a Brooks B17 or a hardshell recumbent seat (both of which qualify as firm, I guess..) I find the wider tires to be just as fast, far more comfortable, and far more capable of handling the odd pothole or gravel. And as a bonus, I don't need tire levers to change wide tires - bare hands do it every time.
SP
Bend, OR
ps - Anomaly, centuries don't qualify as "long distance" in my book, but then I'm a rando.