Estimating work is hard as it is. Using dates over story points as a deciding factor can add even more complications, as they rarely account for the work you need to do outside of actual work, like emails, meetings, and additional research. Dates are also harder to measure in terms of velocity making it harder to estimate how much effort a body of work takes even if you have previous experiences.
Story points, on the other hand, can bring more certainty and simplify planning in the long run… If you know how to use them.