I regularly use archive.org to avoid the distorting and invasive pop-ups that regularly litter web pages these days, but I feel this is a bit of an overreaction in this case. I suppose they could position the sign-up area at the top of the page (or even in the middle). But tbf, the point of Substack is for readers to stay in touch with their favorite writers and for writers to build a readership. Thus, prompting the reader to subscribe is highly relevant. In that way, though I dislike the intrusiveness of pop-overs, it doesn't seem grossly offensive to me in this case. Certainly not to the point of "fku substk".