There is room for both. There are open source alternatives to this service, which a couple of folks on this thread have already pointed out. However, not all

There is room for both. There are open source alternatives to this service, which a couple of folks on this thread have already pointed out. However, not all teams are scaled to run and maintain a Jenkins server so there is certainly a need for such services. Often the price point is low enough that I am happy to get myself out of the business of maintaining infrastructure so that I can focus on the product I'm building.