in defence of using ue5 for a 2d platformer, you still get a ton of features to help you build out the platformer, cross platform support, and you can reuse your knowledge across projects.
it's kind of the same for react. yes you could build one thing in vanilla js, another thing with htmx, and then a third in react. or just build all three in react and be done with it.
modern web dev is actually pretty simple now, there is still a stigma around webdev from the olden days but spinning up vite + react is trivial, doesn't pull a ton of dependencies, and makes it easy to build anything you want. yes you can still overcomplicate it massively but that's on the dev at that point.
it's kind of the same for react. yes you could build one thing in vanilla js, another thing with htmx, and then a third in react. or just build all three in react and be done with it.
modern web dev is actually pretty simple now, there is still a stigma around webdev from the olden days but spinning up vite + react is trivial, doesn't pull a ton of dependencies, and makes it easy to build anything you want. yes you can still overcomplicate it massively but that's on the dev at that point.