Earlier quoted context omitted.
Google Maps is famous as a pioneering use of AJAX, not as an SPA. Whether it is or is not an SPA at present is largely immaterial. There are many ways to create interactive experiences without full-page reloads, and going full SPA is just one route.
Sorry, I'm a bit confused about the difference between an Ajax powered page vs an SPA
Putting bits of AJAX into a web app doesn't make it SPA. Lets say you have a CRUD web application that is tax forms which end up being 5-10 "pages" printed. Then as a SPA you would have to load all the code to generate the 5-10 pages of forms, validation, logic, etc. onto a Single Page. This single page would be where everything is done, the URL would not change and the end user would have a seamless experience.
If the goal is interactivity and seamless operation to the end user, attempting to mimic a desktop app, there are multiple paths to achieving that goal. Limiting the design to a single page seems sort of contrived and a "do it because I can" type of approach, absent of user requirements - in my opinion.