People have always questioned things. The readers aren't changing. Their ability to communicate with the author is changing.
Now there is a thriving ecosystem around these discussions. People put forth their theories, other people debunk them. They spend hours reading and writing fan fiction to flesh them out. They immerse themselves in the act of participating in the world-building in a way that was simply not possible before.
There is a feedback loop here - more engagement leads to more controversy leads to more engagement.
Certainly some people have always questioned things, but it seems impossible to me that these new ways of engaging haven’t resulted in changes in the quantity and qualities of these types of fans/readers.