Dawn of war 1 didn't have any sort of account as far as I can remember, but it also didn't have major story choices. It's arguable whether dark crusade / soulstorm had any choices either since there is an official cannon version.
DOW2 on release used games for windows live. Same with Chaos Rising (which included some interesting choices). And then by the time retribution came out, GFWL was removed and then it was associated with a steam account.
Now with the revival of Relic under Sega we've created these new Relic/Sega accounts. As far as I can tell though, these accounts are not actually backward compatible with DOW1 / DOW2. Is that correct?
A tangentially related question then is, will DOW3 be completely standalone (or will it use DOW2 data to help inform the campaigns)?