Don’t mean to turn this into a pissing contest as to what type of riding style is ‘better’. Hopefully we can discuss this without it getting too heated.
I agree with you that more riders equals more visibility but for me that is offset by worrying about the guy behind me. Someone 1 second to my side is not enough room for me to very comfortable, especially if I don’t know what level their riding ability is. Would you like that woman in the hat 1 second behind you on the road? It would make me nervous.
Aside from safety it reduces my fun as even in the roads at the end of the video the group is riding in staggered formation. I would drop off a little and then catch them easily (and I am not a fast rider) as I used all of the lane in the corners. If I have to go round a corner as if following a rail then I am not having any fun. This problem is exaggerated by putting the slowest riders at the front (MSF recommend advice I believe) which means everyone goes at the speed of the slowest rider. It’s just not a style for me and my rides with this group will be less frequent during the summer months as the group size swells.