On smaller screens I’m kinda ok with scroll bars appearing only when scrolled, but what’s with no scroll bars at all on some websites? That irks me like nothing

On smaller screens I’m kinda ok with scroll bars appearing only when scrolled, but what’s with no scroll bars at all on some websites? That irks me like nothing else. I can’t even figure out how long the page is and whether I can finish reading it quickly or need to save it for a later time. What do the designers gain from such user hostile designs? And how are people paying for such designs without any oversight or reviews?!