Simple architectures work well, until they don't. A good example is ye olde ruby on rails monolith. Dead simple to set up and iterate quickly, but once you reach a certain organization and/or codebase size, velocity starts to degrade exponentially
Complex architectures work well, until they don’t. Fixing complex architectures is much harder than fixing simple architectures. So would you prefer a simple architecture or a complex one? The answer should be obvious.