I am having these discussions daily at work. Our main web application is a React/Redux app that uses server-side rendering for SEO and social-media sharing purposes. The temptation of having one and the same codebase both on the server and on the client was very powerful. The beauty of having the code modularized into clearly defined components was also an attraction. And I am still not convinced that it is necessarily a bad architectural decision. But the sad reality is that our app is bulky and yes, suffers from the symptoms he is describing.
And meanwhile, our company lacks manpower and will power to re-write our web app in a more performant manner.