I wouldn't call my Masi and my Mondonico crit bikes, they're both great fast distance bikes. Neither, for example, have the extra-steep head tubes, especially the Mondo. I just think Greg preferred more seat angle in a fast distance bike.

Because not all other riders rode for Guimard or other French teams, they weren't exposed to this seemingly French style of fitting a racing bike. If the other racers who turned builder were on an Italian team, they probably continued that style. The Italian style of steeper seat tubes goes back to the '50s: look at the pics on-line of early racing Legnanos, Frejus', Bianchis, Masi, Cinelli, et cetera.

Seat tube back or not, these are all some of the most effective fast distance bikes (stage racers) ever, both the Guimard-style and the CONI style.