They can sprinkle some tasteful adverts on the Flexbox article and make their money back in < 03 years.

as other comments have pointed out, DO have a strategy of writing great documentation, for stuff that isn't immediately there's (e.g. iptables/ufw, terrafrom, docker etc), these benefit people both using their platform already, and draw others in (find docs, hey these are useful, what else do they do?).

I could see them using this for both subtle (the header/footer links etc) and more "sponsered" content (i.e. links to DO AppPlatform in an article/tutorial about next.js etc)