Mobile cores are usually power/thermal constrained. Still parsing HTML or running an ungodly amount of JS that then spits out that HTML on the device is not that big of a difference, both kill the battery charge fast :)
As I said, servers cores are also power and thermal constrained. A16 is like 50% faster than high frequency latest and greatest Sapphire Rapids single core. 50%.
Businesses are not server-side compute limited. Ask any business basically. They would gladly trade more of their own CPU power & heat for more time on the site/service from their users.
I didn't say they were compute limited, did I? Still, Pouring unlimited funds on more servers so they can sit <10% idle for best client performance is a great way to light money on fire.
Faster -> more responsive. The client's cores are faster, even on mobile. If that's such a great trade, SPAs are potentially better than dynamic SSR.
