Firstly what I usually do is I quickly scan with eyes over the page I'm seeing and it gives me understanding what to expect.
Secondly, different words and different sentences require different paces of reading, so the pace can't always be constant like this. And for different people, different sentences, paragraphs have varying ease of understandability based on past experience, so I don't think it would even be feasible to adapt the pace by "how difficult" a sentence is.
It more like makes me feel claustrophobic and as if control was taken away from me, almost in panicky way I feel like I have no control over the content or ability to think about the content for any time.
I'm frequently seeing this UX being trending in many places, besides reading as well like filling out forms - TypeForms?? If I don't see the whole list of expected inputs/forms, it's much harder to know in many cases what data is exactly expected from and for which reason.
It seems it just makes everything worse as it removes all the info about the context so you are left without any feeling of control or context, just randomly doing something.