Hugo can be that simple if you don't have a complex frontend template. As soon as you want to make a SPA (or SPA-like experience), use a framework like React/Vue/Svelte/etc., or even try out stuff like TailwindCSS you're going to get sucked into the deep rabbit hole of bundling frontend assets, webpack/esbuild/etc.
So you kind of have to decide, are just static templates and static assets all you need? Stick with Hugo and enjoy the speed, simplicity, etc. There are some even simpler alternatives you might enjoy too, like mdbook or mkdocs. Both are more oriented towards technical docs but are similar to hugo at their core--send in some markdown (in the case of these tools you don't even need frontmatter or other schema) and get out some HTML.
If you're building something fancier or using more complex frontend setups then... there's no perfect answer right now. It's all about balancing complexity of the build system with what it gives you in the output. IMHO webpack and gnarly dependencies can be tamed pretty well with a simple docker container. Spend some time getting your perfect workflow setup, chuck it in a container that a CI system can run all day, every day without fail, and you'll be pretty well setup.