If you you have good handle on who your customer base is (current and target), then no, you don't need personas. Just use real data. Where I become dumbfounded is when large companies with mountains of customer data with complicated segmentation and profiles continue to rely on just 5-6 same personas.
The money dried up really fast (they where extremely expensive) and the design just sucked but boy did they have meetings like nobodies business.
It doesn’t hurt that doing it makes you feel like you’re doing something useful, it gives you a shiny deliverable, ... but in the end there likely are better ways to answer the kind of questions you really want to answer, and many of them involve making the actual thing vs making things that only serve the planning of the making of the thing.
It is a useful sales tool as then the people people management types who can easily relate to the persona.