Valid point here. But to shed some light on it, my site is built in a way that is geared more towards loading quickly and with the necessary data before bringing in things like pictures and ads. Different pieces load at different times and in a certain order to improve the readers experience. Google has no way of knowing the difference. They see that as render-blocking as opposed to content optimization.
I could probably do something about the image compression and image headers. I’ll agree with you there.
But PageSpeed Insights doesn’t play nice with sites that have a fair amount of client side rendering. Any Discourse site is the same. They do quite poorly on that rating system. It’s a pretty common complaint with PageSpeed.