I think the biggest benefit for many people is that CTEs allow them to write complex SQL in an easier way. Moving to derived tables just seems harder for many people writing queries.

A CTE can be written first, meaning write part of your SQL that you need, then once you enclose it in the CTE formatting, you add it like any other table or view, without having to create those objects.

However as someone that's been writing T-SQL for over a dozen years, I'm not sure it's that much easier for me. It is slightly clearer in some cases, but for the most part I find relatively few queries where I'd use it. I think that's an experience thing