They log every single pageview to SQL Server. There are plenty of writes to various other counters, recommendation system, message inboxes, analytics, etc. Also the ads system, although I'm not sure how much of that is still 3rd-party.

Yes it's read-heavy but there's still plenty of work done in assembling a page. It's definitely not as simple as caching at the CDN edge for every hit.

IIRC most of the "real time" stuff is done on Redis, for which this QPS load is usually a joke (depending on requests of course, but counters etc are easy)

so, would you mind showing any non-FANG, but write heavy site? Besides that, even the operation of most social networks should be very easy to be split into town-sized instances with batch-updates in-between instances (see mastodon specs https://github.com/tootsuite/documentation/blob/master/Runni...). What actually costs a lot is constantly surveilling all user interactions, data-warehousing that and playing out ads. None of which is necessary, and a 20ct/per user/per month should cover the actual service nicely...

Most any saas offering is going to be very write heavy in comparison.