Server-Side rendering tightly couples your front-end to your application server. Scaling the site means scaling up that application server. A bug in one "page" of the app can cause the whole application server to go down.
If you leverage client-side rendering then it's easier to decouple your front-end from the back meaning you can take advantages of things like segregated micro/serverless services and progressive web apps. You can also re-use those services for multiple applications, making it easier to keep the business logic OUT of your pages and in an API layer where they belong.
I agree that SPAs are not the solution for everything, but I think that server-side rendering is on it's way out.