The server load from a server-side rendered page vs an API call that returns JSON is... very minimal.

Unless you're building at great scale, it's such a negligible difference that it really shouldn't be part of your decision making process, IMHO.

>One advantage of pushing the computing on the user-side is that it reduces the load on the server:

But we don't need complicated frameworks on the server, keeping track of changes in a shadow DOM and updating the real DOM afterwards.

The server will likely just use some html templates in which it will replace some variables with strings and numbers. Easy peasy, both for the server and for the developer.

Since all the clients have to do the work, doesn't that result in a net increase in electricity consumption? Since most electricity comes from fossil fuels doesn't that in net hurt our battle against climate change?

So by spending thousands of dollars on developer time we can save dozens of dollars on server costs? ;)