You can get the best of both worlds with Gatsby plus gatsby-plugin-no-javascript. Gatsby inlines critical css and small images and does just about every trick available to minimize page load, then the plugin kills the hydration. The plugin can run on a per page basis, so you can still keep your hydration on your pages that need them. For complex webapps that also have marketing/documentation/landing pages, it's a really nice combo.

Gatsby devs or advocates would argue removing the js removes the preloading of pages that helps make Gatsby faster. Although this is true, in my experience removing hydration is often a better trade off. It of course depends on the site.