They absolutely were, yes. There are very valuable application profiles where FoundationDB's design is excellent, and you can see that from its internal usage at large companies like Apple and Snowflake.
Yes, one of the nice things about FDB is it has extensive design docs. Optimizing for reading more often than writing is obviously a pretty normal design choice, outside of log ingestion you'll normally be reading more than writing. There are people using FDB for logs (snowflake iirc?) and it's been optimized for that sort of use case more in recent years, but it's not like it was an unreasonable choice.
Snowflake uses FoundationDB for warehouse metadata in the control plane, IIRC. It is not in the data plane path for log ingestion or other warehousing tech. That said the control plane is, uh, pretty important!