There are still some processes that require a waterfall method for development, though. One example would be if you have a designer, and also have a front-end developer that is waiting for a feature to be complete to come in and start their development. I know on HN it's common for people to be full-stack developers, or for front-end developers to be able to work with a mockup and write the code before a designer gets involved, but there are plenty of companies that don't work that way. Even if a company is working in an agile manner, there still may come a time where work stalls until some part of a system is finished by another team/team-member, especially in a monorepo. Of course they could change the organization of their project, but the time suck of doing that (like going with microservices) is probably going to waste quite a bit more time than how often GitHub is down.