This is the reality of reading twitter on mobile if you aren't logged in/using their app though.
This is actually my problem with that website and the main reason I hate Twitter threads. Twitter doesn't let me open anything in a new tab properly, sometimes (like last week) opening images in posts doesn't work for days, and I stopped using the site because after about a month the notifications stopped showing anything new, I literally had to scroll through my own profile and manually look for answers to my posts! In the best case this is an unreadable mess where everything has to be unfolded like a messy origami; and sometimes this reloads the site, sometimes it doesn't, either way it comes with at least a second of loading time.
I'd like those threads if they were as readable as comments here on HN. But Twitter seems to test how inaccessible they can make their main content without people leaving.
It's more than just a horizontal line. There are icons and buttons in every post, that is, every couple of sentences. Hover-over popups that obfuscate content. Distractions and irrelevant click-bait content on the side and on the bottom. Embedded media (images, videos) behave poorly. Obfuscated external links. Cookie/sign-in banners that take more space than on other websites. I could probably go on if I took another look, but seeing how Twitter is now forcing me to log-in, I can't.
And I think just about every remotely popular blogging platform works properly on mobile, it's not 2005 anymore. Ads might be a problem on some, I'm not sure. But I bet even with ads it's not as bad as Twitter overall. For testing I opened a Blogspot link now with no adblock and there was just one unobtrusive ad on the side, way better than Twitter in terms of readability.