I think we can *all* (caveat—there’s always someone…) agree that preseason polls are ridiculous and rarely reflect the product that will be on the field during the season.
In addition to the exposure/hype that comes from being ranked in these polls, they matter because of pollster behavior. As a whole, pollsters rarely change their rankings based on the relevant performance of a team; rankings change based on who wins/loses ahead of you.
If you start at 10 and win all but 1 game, you’ll likely end up in top 5. If you start unranked and win all but one, you’ll likely end up outside the top 5–even if both one-loss teams are otherwise considered equivalent on the field (not just in w/l). The originally-unranked team will inevitably be behind other 2-3 loss teams whom no one thinks are better, but who started higher ranked and lose too early in the season to be jumped by the originally-unranked team.