The article is a bit confused about what is really about SPAs in general or React in particular. Still it is clear they raise questions regarding accessibility and navigation. In turn, this requires a lot of careful implementation to make sure the user experience is acceptable.

This can indeed quickly become a problem. This slows down everything and can bring with ot a silent killer: context switching. It is avoidable though, there are good strategies to prevent WIP to go out of control.