Not everyone agrees with that. A lot of people think the efficiency of writing code in favorite language X makes up for the added hosting cost. I just don't believe it with how many choices are available now. Maybe that was true 5-10 years ago. Now we have a good 5 languages with maybe 40 frameworks that run less than 3x slower than C. That's really really fast. Enough that you could run anything under top 500 sites with a single machine.

Static CDN hosted react/angular SPA with a speedy backend can serve a stupid amount of traffic even on AWS free tier.