Each team is expected to be largely self-supporting.
That includes UI, documentation, everything.
They can leverage the work of other teams, if they choose.
Once the product has been created, it is then up to them to get the word out about their product in order to get other teams to use it.
So, there is a huge discoverability problem in just finding out what tools exist and what they do.
And each team is largely responsible for policing themselves on compliance with standards, or figuring out what best practices are and then adhering to them.
So, how many employees does Amazon and AWS have? How many two-pizza teams can you create from those numbers?
How many two-pizza teams would you have to have before you start having duplication of effort — or schizophrenic implementation of differing interpretations of standards?