I already have a cross bike (bought new last year) that works pretty well for gravel with a number of gravel races and lots of miles and elevation on it with no problem. A local guy is selling a gravel specific bike that I love the look of but is essentially the same geometry although a little shorter wheelbase and 650b tires.

Other than n+1, why should I buy a gravel bike? Wrong answers only. Bonus points for adressing the inevitable eye rolls from the SO about another bike in the garage.