@chilly_bang I think you misunderstand what prerendering does vs general site optimization - they are not competing with each other, they compliment each other.
Note that on a website like mine (with no JS modifying the DOM on page load), prerendering will implement a 0% improvement to my website performance. There are no JS based DOM changes for a prerendering service to cache - I already built it with a static site generator (hugo).
Even with pre-rendering the core principles of conserving overall bandwidth to reduce latency, reduce mobile device battery consumption and reduce CPU load, reducing number of requests or implementing http/2 to save TLS handshakes, serving images of an appropriate size and format for the content, etc. ALL STILL APPLY whether “pre-rendered” or not. So it’s not either-or here.
You cannot defy physics. The majority of web traffic is now mobile browsers. Majority of mobile browsers have more resource constraints, smaller CPUs, or lower clock speeds, wireless connectivity and not wired, etc. You’ll find all the optimization techniques recommended are catering to conserving resource usage (particularly important on mobile devices).
But at the end of the day part of optimization is… Test it yourself and measure! Personally, I enjoy the technical challenge of site optimization something like a chess game. My homepage now gets a perfect score on WebPageTest, GTMetrix and Google Pagespeed/Lighthouse. Is their some diminishing returns to go from like 96% to 100%? Yes, for sure! It’s unlikely that the last couple percent matter as much as the jump from 50% to 95%. It’s up to you to decide if your use case requires that last 5% of perfection or not…