The stuff about scale not allowing quality resonated with me.
baseless speculation follows!!!
I think large orgs can definitely achieve high quality. but only by spinning up small, totally autonomous teams working on every layer of whatever stack their product is on, one team per product (maybe two if there's some really obvious line in the sand between two different things that talk to each other, but be careful! and make sure both teams are in the same timezone!).
As soon as you start trying to do those things that seem really sensible when you have a bunch of separate autonomous teams - like "hey you're both working on similar features, you should share the implementation", and "oops all our products look different, we should come up with a unified component library", and "we need automated tests - everyone should use this specific tool that we paid for" you run into the big org problem.
My gut feel is that the best way to get some level of coherency without running into these problems is to share knowledge, best practices, examples etc. But never dictate anything that actually gets in the way of any of your teams owning their own shit. Don't make teams use some internal/external library for functionality x, don't enforce processes, don't have a separate design team dictating css styling to teams, don't enforce org wide CI policies, don't have a separate DevOps team handling releases - just hire competent people and let them do their thing. If you do want to try to build something so that all the teams solve the same problem in the same way, you need to get them to use it by making it so good they want to, not by telling them they have to.
You might be able to enforce some baseline level of mediocrity by doing those things, but the only way to achieve excellence is to get out of the way and stop trying to "help".