I wasn't on Brain, but got obsessed with Kerminology of ML internally at Google because I wanted to know why leadership was so gung ho on it.
The general sense in the early days was these things can learn anything, and they'll replace fundamental units of computing. This thought process is best exhibited externally by ex. https://research.google/pubs/the-case-for-learned-index-stru...
It was also a different Google, the "3 different teams working on 3 different chips" bit reminds me of lore re: how many teams were working on Android wearables until upper management settled it.
FWIW it's a very, very, different company now. Back then it was more entrepreneurial. A better version of Wave-era, where things launch themselves. An MBA would find this top-down company in 2025 even better, I find it less - it's perfectly tuned to do what Apple or OpenAI did 6-12 months ago, but not to lead - almost certainly a better investment, but a worse version of an average workplace, because it hasn't developed antibodies against BSing. (disclaimer: worked on Android)