The renunciation of cables in new buildings is simply short-sighted and stinginess in the wrong place.
Once again: it is not about being stingy.
I question LAN as a future-oriented technology. Your insights into 5G mobile communications are new to me. Personally, I rather believe that communication technology (by that I mean everything that communicates, so also devices, not just people) tends to move away from fixed locations toward the greatest possible mobile flexibility. To put it radically:
Anyone who has a landline phone at home today is already outdated. Remote work is another example. No location dependence, whether within the building or worldwide. The discussion here about LAN and bandwidth and please via cable reminds me of the history of telephone networks in industrial vs. developing countries. The latter have practically completely skipped the telephone network technology and only built mobile networks. No one there would have the idea of laying cables from house to house anymore... Of course, the comparison is a bit of a stretch, but I do see parallels.
: your post is communicatively (not necessarily content-wise) "complete nonsense." However, in terms of content, you also describe a pro installation that seems absurd in everyday life for most single-family home builders.