Yes, but like the best simple recipes, the skill lies in picking the right two and using them in the right proportion.

Gins and vermouths both vary a lot in flavor, and a martini is a drink that's all about the subtleties of how they interact. If you get an olive or three in your martini, there's also the element of the olive brine. That could be an incidental amount from the surface of the olives, or an amount added beyond that, at which point the drink is properly called a dirty martini.

A martini is the perfect test of a bartender's skill, just as a plain cheese pizza is the perfect test of a pizza maker's skill.