From my personal experience, people are more likely to read and share threads for a number of reasons:
* They don't have to go off platform.
* the base tweet can be much more eye catching that a link, even with social cards set up
* People may be desensitised to links that lead off-platform, because that's how Ads generally appear on Twitter
Then there are other advantages, like the fact that it tends to encourage you to write in a concise and direct way, with each tweet in the thread being like a bullet point. I often see people retweeting and engaging with a specific tweet from the thread; it's harder (relative term) to do that with a section from a blog post.
I think it's primarily because you put actual content right in front of them, increasing the chances of them getting hooked by quite a bit. Before your blog post has any chance of hooking people, they have to first take the plunge of clicking on it. Threads eliminate that friction.
Those look terrible, like powerpoint presentations that you fall asleep in the middle of. And in any case, the link here was to a tool that was basically using blog-like editing tools to write blog-like threads. So, why not just blog?
Agreed, what would be better would to maybe put the engagement stats(faves,replies, etc) to the right, expand replies to each tweet when clicked on pop from the right and then descend, but the thread itself a contiguous block of text/tweets all the way to the authors last tweet in the thread.