You do know that it makes no sense that it's faster pace having less party members right?
The game concept is totally different from DoS.
Having more actually lets you end battle sooner because of the limitations of DnD combat. Most can do one or two actions a turn, with more party members, it means you get to attack more.

If this was DoS, for sure, we'll watch this guy buff his character 20 times in one turn than finally proceed to wipe the map by himself, but so far the new battles is nothing like that.

Storywise the number of party members don't matter, it's all on the writer, we can have one member and it'll be a good story if the designer behind it does a good job. But comparing the two game makes no sense as well, one game does revolve around the idea of playing a tabletop game with others in a group, some folks have no friends we get it, so they like less of a crowd and now the other game... the other doesn't really relate at all to the game design, it's two different world. We only compare DoS to this because of the fact that it's the same company.

People do make a lot of valid points for 6 men, and tbh, if you want 5, 4 or 1, just do you, letting people choose and have more options is never a bad thing. I don't see why people whine about how other people plays,n when most likely, we'll never play together, we're more bound to play with our friends and family.