No, I think that this current information is obsolete and most of it is redundant.
IIUC, it is now your intent to add information about the dependencies needed for KDE which makes this further unnecessary for those that are just building from scratch.
In general, I would recommend the BLFS book to anyone that is building from source, so I think that the link is now in the proper place. That is unless you intend to duplicate that material in that much detail. Have you read it?
I can replace the obsolete notes for the old versions with some notes on building the more obscure dependencies and possibly other relevant information for building from source that isn't currently covered by the BLFS book.
No, you misunderstand me. I'm proposing to delete all the obsolete material and replace it with your recommendation of the BLFS book.
It is OK to delete the obsolete material. I think that it is all covered in the BLFS book for version 4.10.x. There are some more obscure dependencies that are not covered which I could add some notes on those that I have knowledge on from personal experience.
Putting the recommendation on the BLFS book there to replace it would be redundant because people installing 'Linux from Scratch' would have already been to the website and already be familiar with the book.
There are also people that are not using the LFS distro that just want to build KDE from source (for various reasons). What I want to do is to suggest to them is that a source of instructions on how to do this is to be found in the BLFS book. That is, unless there is an equally detailed tutorial on how to build (the release version of) KDE from source on KDE Techbase. My tutorial, which appears to have been deleted, was not nearly as detailed or as complete (but at the time it was written, the subject was not covered by BLFS).