For medium to large projects, SPA or not basically boils down to the question where you want to manage the state and logic, is it at frontend(SPA) or backend(MVC,CRUD,etc), you still have to do that somewhere with complexity.
If the website is simple then definitely no SPA is needed, either htmx or alpinejs or vanilla can get the job done.
Unless you're building a local first app (i.e. google sheets), the backend for most web apps is the source of truth. SPAs that lazy load tons of data on the frontend are introducing a lot of complexity trying to sync state between the frontend and backend.
Having a single source of truth by push things down into the backend is a godsend in terms of limiting complexity.
or you have to test Model View and Controller at the backend, the backend can be messy as well over time, not to mention it has to sync with frontend team. it depends on team experience, e.g. stronger at backend or frontend and more importantly, how they work together.
If the website is simple then definitely no SPA is needed, either htmx or alpinejs or vanilla can get the job done.