I have thought about this a bit. My take is that almost all of these blog posts are from one-off contributors and not one you'll see over and over. I kind of see it as them taking their shot as making you a recurring visitor or recurring reader of their content. I've personally never heard of Statista and don't think I ever will again, if past experience is an indicator. I don't fault them for that, although it is slightly annoying.

Though if it were me, I'd personally wait until someone was partway through the article at least before presenting a newsletter sign up. There's no way I'd sign up for a newsletter before I saw the site's content.