Why does traditional software seem so needlessly complicated when Web-based, cloud and mobile alternatives seem so much simpler?
For the same reason that restaurants put more food on your plate than your appetite can take. To make more money out of the same sale. One meal in your plate, one in a box. They compete with whoever would have fed you the following day.
Function creep and bloat exist because sales and marketing costs represent over 80% of the costs of “traditional” software. They also exist because intellectual property is hard to protect in the software industry. Finally, they exist because they can (PC’s have processing power to waste).
In contrast, Web-based, cloud, and mobile applications are generally simpler because they are using "lighter" clients, new development technologies, and new business models. With new platforms, things can be done in radically new ways. As incumbents grow in size and complexity, newcomers must grow in innovation and simplicity.
Function or scope creep does not exist in Open-Source software because there is no sales motive for it; no need for differentiating features and no need to create new revenue through the satisfaction of dubious peripheral needs.
Rather, the emphasis is on clarity, simplicity, modularity, and robustness. Less moving parts means easier set-up, better interoperability, better scalability and easier troubleshooting.
There is more pull than push in Open Source software. Open Source wins the day because it is not about profit maximization. It is about the satisfaction of a user need. It is in putting this need first that programmers collaboratively design the best possible product (for themselves, their employers, and/or for others). From Google to Tesla, the most successful tech firms rely on Open Source and share much of their intellectual property (e.g.: Chrome/Edge, Kubernetes, Docker, TensorFlow, PyTorch…).