Actually, it is, in a diagram right at the top of https://github.com/Mooncake-Labs/pg_mooncake.

However, the Venn diagram does not tell me anything useful, so I agree with the sentiment. Would love it if someone could explain what mooncake is good for and what its strengths and weaknesses are vs Timescale.

Its ability to store data on S3 is in paid cloud version only, last time I've checked.