You contradict, and invalidate yourself, in your own argument.

> they (the local pub) would have a much harder time selling something unique

> Scale ...becomes the default choice

Scale and monopoly removes choice and uniqueness.

There are people that love Starbucks, there are also people that love their local coffee shop.

I don’t those two thing are contradictory, it’s just that you are assuming you don’t get uniqueness inside a monopolistic platform, which is only partially true. The platform is fixed, but you get uniqueness inside the platform, with the content and contacts you follow. Facebook, reddit, etc. are not the same experience for all users. Comparing a network, where each vantage point is unique with Starbucks, which has maybe 50 products, is not an apt analogy.

I tend to avoid larger pubs because the quality of experience in smaller ones tends to be better.

Quantity has a quality of its own, and it's not always a good thing.