It's kind of a scam, because anyone with an AWS account could do the same thing, for the same cost (and have space for 20+ static websites) ... but not everyone can deal with AWS, nor can everyone edit a website.
It's too bad Wordpress is hot garbage, and I'd never touch (or recommend that even the most tech illiterate person should touch) that garbage fire of an app.
You actually said it yourself in your comment: "not everyone can deal with AWS, nor can everyone edit a website." Stelae is for the second group, the WordPress-editor side, who don't want to run public PHP to publish. The €19.90 isn't margin on the hosting; the hosting is yours, on whatever provider you pick.