lots of good responses in here, i'd just like to throw in that socialist kellogg added a fourth variety of cereal to their production at some point (not sure if that's in this article but anyway) so there's an example of workers owning the means of production increasing variety.

https://www.fightbacknews.org/2021/8/8/venezuela-workers-take-over-kellogg-factory-now-known-socialist-kellogg

if there was no competition, every soda fountain could be a coke freestyle and you'd be able to get pepsi flavors and weed out of it too.