I think it's a big misconception that rendering code is responsible for most of this bloat. The great majority in my experience comes from tracking scripts and

I think it's a big misconception that rendering code is responsible for most of this bloat. The great majority in my experience comes from tracking scripts and adware that get layered on top. This can be just as true on a React-based site as it is on a classic server-rendered Wordpress site, and is often out of the hands of the actual engineers. I suspect Google Tag Manager has done more harm to the web experience than any other single factor.