The idea I was trying to get at was using redis to store data traditionally reserved for OLTP workloads.
> Pretty sure we all can think of some pretty high profile examples of NoSQL + structured data working very very well at scale.
Well that's the thing, you very rarely hear of companies who cursed their decision early on to use NoSQL when they realized that their data was structured but in 20 different ways over the lifetime of the product. Some datasets only need light structure (key/value, a loosely defined document, schema-included documents), and other things should probably have a schema and be stored in a database with a tight grip on that schema and data consistency/correctness. Please don't use redis in that latter case.
1) 99.9% of internet-facing/adjacent businesses are not Google and will never reach even 1% of Google's scale
2) Proto + BigTable is very different from just throwing stuff in redis/mongo. Proto schemas are compile-time enforced, which is great for some teams and might slow others down. Google enforces more discipline than your average engineering team -- this is overkill for most engineering teams.