If you're outsourcing operations to AWS or whomever, a couple largish instances and a couple supporting services can get you pretty much that same thing, for a bit more money and a bit less control over performance-consistency.
All that HA/scaling/clustering/cloud stuff is expensive, not just in monetary terms, but in performance terms. If you don't actually need it, a high percentage of your compute & (especially) your network traffic may be going to that, rather than actually serving the product. It also adds a hell of a lot of complexity, which comes at a significant time-cost for development, unless you want your defect rate to shoot up.
> But if more developers just learned how to make a website on linux, with a db, a webserver, and an application.
And hell, nothing's stopping you from writing 12-factor apps and deploying containers, and scripting your server set-up and config, even if you don't go straight for heavy, "scalable" architecture. Even if your server's a beige Linux box in a closet. Enough benefits that the effort's probably a wash at worst (hey, documentation you can execute is the best documentation!) even if you never need to switch architectures, and then you'll have a relatively easy time of it, if you do end up needing to.
