What is an example of a "high-end page-layout program" referenced in that document? I mean, of course I assume they exist for professional type setting, book publishing and such, but I have never seen or heard of the actual software.
I am not a typographer, and I’ve never used it in a professional capacity, but v1.6 (early 2024) improved Scribus a lot. I’ve used it and liked it for some personal projects for years, but the improved typography in 1.6 is big.
I am not gonna argue if they are correct or not but the reality i've experienced is that at minimum socially the printing industry is married to InDesign.