I agree, it doesn't make a difference as the seats are not assigned.
Where it WILL make a difference is if the lowest price fare category does not have enough seats for your whole party. Ex: After inputing your information on the reservation page (including number of people as 5) you see a promotional fare for $49 one way (wishful thinking), but it is showing not available for the time you want. Go back to the reservation page and change the number of people in your party to 4, then if still not available, try 3 and so on. Sometimes you will find availability in that fare class for a smaller number of people and you can at least get the low fare for that number. Then you can book the rest of your party at the higher rate.