That's right. The key difference is using row-based vs column-based databases (i.e. OLTP vs OLAP). Any good database person should be cringing at the thought of using Postgres (or MySQL, Oracle, Sql Server, etc) for pulling reporting data.
That said, no regrets using Postgres there. If we started with Clickhouse the project could have not launched as quickly as it did, and that would have given us more problems.
If you were storing billions of rows per day in MySQL, SQL Server, or Oracle, it still wouldn't be able to handle it, would it?