I wish front-end developers would use the right tool for the right situation. Not everything is a nail!

Forms are a great example. Browsers and back-end languages have supported those very well for a long time without the use of JavaScript.

Routing is another thing browsers and back-end languages do very well.

The SaaS we are building is in Laravel + Vue. Laravel has a powerful validation engine and top notch routing and session management. We leverage those 100%.

Vue shines for user interaction. Instead of a single SPA, we usually have one per rendered page (i.e. User Interface). Works very well.

I haven't found any downside to this approach vs a full-blown SPA. Only benefits.