When buying chairs, it would be most useful to search by seat depth...

1st, regardless of your height, you're likely to need a certain seat depth. I'm about average height, 5'4" or 5'5", so I need about 16", certainly no more than 17". Most chairs are at least 19" and I have to either sit up front and not get back support, or sit all the way back and cross my legs. 2nd, you're rarely going to be able to spot a chair's seat depth from the chair's description or from sample photos. Maybe if they include a diagram, but that takes more time and a closer look. 3rd, you're usually going to be able to get some idea of a chair's purpose, padding if any, style, etc. from the chairs description or from sample photos. So it would be easier to search by seat depth and sort through the results than to search by function, select each result, and check whether it lists the seat depth.