Your first paragraph is exactly my point. Because in an SPA, you have to handle it in both places, not only on the server. That makes it twice as hard as an old fashioned server-side mvc page.

> Data being "an sql query away" on the server is similar to being "an AJAX call away" on the client.

This is a bit disingenuous, since sql calls in most back end languages are synchronous. Also an ajax call needs to update the UI to tell the user something is happening. This might mean disabling controls, showing spinners etc. All of this goes away if you only use server-side rendering since form requests are natively handled by the browser.

> It's certainly not the case that asynchronicity makes you write shit code.

But it expands the number of cases you have to deal in the UI, to show all the loading states, error states etc.