If a non pre-season ranked team starts out 3-0 the only way they move into rankings is if those wins are against teams that were either in the rankings or are considered upper tier. So winning against cupcakes doesn't hurt the SEC teams since they started out in there, but it does not help vault the "surprise" teams into the rankings.

PAC12 was hurt by USC losing to a team perceived to be average at best.

It probably won't ever happen but imagine how different the polls might be if the first one wasn't until first week of Oct.