until recently you were right about driver support. however windows being THE platform even back then wasnt an issue.
not only personal use but having to support many other arduino users last couple years i found ftdi a constant nightmare while silabs tended to just up and run. both hardware and software incompatibilities etc. for example 6 pin ftdi that used the correct dtr signal were rare or expensiive whereas cp1202 easy to find and cheap. and then theres was the chasing port numbers around depending on usb port used. so if you were a linux fanboy or sparkfun "victim" then ftdi didnt seem too bad. but if not fiddling with drivers and staying out of the poorhouse were goals then silabs is way to go.
ps even now its hard/impossible to find 99 cent ftdi with usable reset pin.