The author is talking in context of Frontend system i.e. javascript only. In SPA, a single app consists of all your frontend system. hence has a high scope. W

The author is talking in context of Frontend system i.e. javascript only. In SPA, a single app consists of all your frontend system. hence has a high scope. While in MPA mode, js is split across multiple pages, and each page has a narrow scope for the javascript code to function. Hence MPA will limit power and misuse of javascript