I think some people have just gotten used to the "Instant" nature of lots of media nowadays, and are used to having everything fed to them in short, quick, digestible chunks and have lost some of the capacity to patiently work through and experience a slower & more involved story.
We live in a post Game of Thrones world, a tremendously popular show that was praised for its slow burn, realistic nature and shifting viewpoints, where people waited for more with bated breath for years, and its downfall was not properly taking its time with itself.
I don't think it's an audience issue, I think it's an author issue. You have to know what you are working with. If you have 15 pages a week you can spend an entire month somewhere else. If you have a movie or a book you can be more secure in its slow burn nature because the rest of it is right there.
If you are working with 30 pages a month you can't spend multiple months someplace else so early on, especially when you put youself in a situation where your general world building depends on NOT having your main characters around, instead of involving them and being a reaction to their actions. It makes it feel fractured and glacial.
Add to that the fact that the other characters being set up don't even have a direct connection to the main pair (only a symbolic one), it was coincidence and curiosity that fueled the other side of the plot which makes it feel even more fractured. The story could start with the sudden dissapearance of a random noble woman we didn't see or know and it would make as much sense.