Well, you shouldn't judge me so fast. I have an MBA with marketing and I have been working on marketing for some time in my life. So I am aware what a marketing plan involves, and promotion is a small portion of it. I cannot suppose the founders knew all about marketing, but I would expect them to spend some money in promotion even if it not wise money.
Maybe you like this more. You have to do some marketing: define your product, know your users, define your goals, find the channels where your users are, target them, promote your product to those users in those channels, measure the results, analyze what happened and rinse and repeat. (that was also a small definition because marketing is still more)