You don't need an SPA to handle incrementing a counter. If a page needs dynamic behavior you add JS to it, whether it's just adding an in-memory counter or an API call to store and retrieve some data. It's not difficult to write JavaScript.

The problem with SPAs is that they force having to maintain a JS-driven system on every single page, even those that don't have dynamic behavior.

What's the business usecase for incrementing a counter?

We can sit here all day and think up counterexamples, but in the real world what you're doing 99% of the time is:

1. Presenting a form, custom or static.

2. Filling out that form.

3. Loading a new page based off that form.

When I open my bank app or website, this is 100% of the experience. When I open my insurance company website, this is 100% of the experience. Hell, when I open apartments.com, this is like 98% of the experience. The 2% is that 3D view thingy they let you do.

Let's be honest -- the alternative is an API call with poor or no error-handling with the brilliant UX of either hanging with an endless loading indicator, or just flat out lying that the counter was incremented...