What is the importance of relative chronology to a historian

Relative chronology is the definition of events that are placed in chronological order, relative to the time they happened. (You need not know the exact date, though).

A historian is someone who studies the history based upon a specific period, social phenomenon or a geographical region.

Based upon the above definitions, I would think that: it is very crucial for a historian to have evidence as to what they think happened. Like a Lawyer with a trial, you cannot simply state a hypothesis and leave the audience questioning your methods.