One very important point against SPAs is URLs. URLs are central to the design of the web. Lets say I want to talk about a particular commit on github. I can just pick the URL for that commit and email it to someone else. They can click on the link and land directly on the commit page. If it is a single page app, I will have to tell them 'Go to this URL, click here, and then click there' etc.

Same case with blog posts. Sites like HN would not even exist if everyone published all their posts in SPAs.