It is just a static website for crying out loud.
But once I got around it, it gave me a score of 100 in performance and 80 in SEO just out of the box. Images are resized and inlined if need be; critical CSS is rendered first; the plugins added niceties like default anchor link in Github. And I could use React components to organize everything, which is a much more ergonomic way of doing reusable markup compared to server-side things like Rails partials.
I would've needed to spend weeks if I had to get here from scratch. Gatsby is bleeding edge and it does best practices - including performance better than most other static site generators. I think the web is only moving forward - there is cambrian explosion of new untested and often ill-thought ideas, but the good ones will survive in the long run.
In case of Invision it seems like images / render blocking css that was added outside of Next.js are the main culprit. I've reached out to Jon Wheeler who works on the marketing site to make him aware.
It took me 5 years to realize that "bleeding edge" != "best practice".