Ask HN: Who does online joins anymore?

This is probably the only place I can ask this and get coherent answers.

Do people really still do online SQL joins for read type queries that tolerate eventual consistency (this is the most common type of read btw)?

If so, why do joins? Why not materialise the correct shape of the data and use it directly? Surely storage is cheaper than having to spend compute doing online joins. Doesn't doing joins online hurt latency?

I could be missing something obvious. But if I am right, in what case do online joins make sense?