What is caching?
This is also true for Web apps that do not have meaningful amounts of client-side code.
> Caching also works for client side rendering
There are obviously a lot of differences in how caching works, but client-side caching is generally strictly worse than doing so on the server. Using the e-commerce example in TFA, every browser has to maintain their own cache of the product information, which may include cache-busting things like prices, promotional blurbs, etc.
The server can maintain a single cache for all users, and can pre-warm the cache before any users ever see the page. Adding fragment caching, which allows parts of a page to be cached, a server-side caching strategy will typically result in less total work being done across the user population, as well as less work done at request time for each visitor.
As an extreme example, something like https://www.photopea.com/ would be a nightmare to use if it was server-side rendered. Or consider something like Google Maps. For things like ecommerce that are mainly focussed on presenting information I agree that client side rendering doesn't make a whole lot of sense. But that isn't the whole web.
