Because they really offer that.
Most startups, especially in the early phase, work in a reactive manner. They try to catch The Big Fish that will pay their bills. Until they get there they have to live off of the smaller clients, and as they need all the money they can get they have to react to all of the small clients needs or they loose them.
It can be crazy most of the time, and what j writes is not far from the truth (unless the other 3-4 people are good at management).
Now to the question whether programmers care about it… well, it depends. I do like it, thatʼs one reason I work for a startup. The last 18 months was all about reactions. We also caught our first Big Fish, but we had to work hard for months to keep them and prolong their contract and basically sell us to other big companies. What is coming now is a year of spinning down to operations speed: we will need less features, and we can prioritise down small clientsʼ needs in favour of the big onesʼ who, in turn, can wait a bit longer for the solution. And once all the rough edges are taken care about, I may move on to another fast paced place.