FWIW, I chose to make my side project I've been working on for the last couple years an entirely vanilla js SPA. The biggest downside I've noticed vs using some

FWIW, I chose to make my side project I've been working on for the last couple years an entirely vanilla js SPA. The biggest downside I've noticed vs using something like React is my speed of development is much slower. The upside though is the code itself is extremely efficient / packages sizes are small. For my own project this is great - I have no deadlines, and half of the process is me just enjoying writing the code. For an existing company the demands are different. Not only are there time pressures, but aligning on something like React means you're introducing convention into the code. Hiring people who already know this convention is easy. Vanilla js, even with webcomponents, just isn't quite there as far as convention and speed go, and there isn't a rich community around it. Is it perfectly able to do the task at hand? Absolutely, but at a price most companies aren't willing to pay. React is the easier of the two.