I have a story about a team that did this. They built an app using "good old" stuff and spaghetti features into it until it's impossible to add anything more, then spent a year rewriting everything in angular just so they could continue working on the product. It was probably not only a problem of a tech stack, but if you know that you need an SPA that is going to need to scale and have more components, it's only a waste of time to try to do it with vanillajs/css/html imo.