Two years ago, I started a new company, and decided at the outset to avoid using any heavy JavaScript SPA framework. We stuck to simple server-rendered html and only use progressive-enhancement style JavaScript.

Our app was fast, and simple, but it also came at a cost: we were limited in our ability to take rich UI elements off the shelf with an npm package. We had to do a lot more work to provide a rich user experience. Everything took longer, and the user experience was worse as a result. We cared, but sometimes you don't have time to carry through.

The company failed, and I don't think react would have saved it. But I can tell you first hand that righteous adherence to "simplicity" didn't help either. It's always a trade-off.