That it is not a good idea to simply install as many APs as possible. Just because you are happy with that in your reference house does not mean it applies to everyone. Even if you find it hard to believe.
Sure, cables also have to be paid for, but that was not the question...
What else? When the question is whether to lay cables in every room or to ask about WLAN as an alternative.
Because he can't imagine what cables are used for.
And why reference house? What are you trying to convince me of now? I don't find that hard to believe - just great, the level on which you're approaching me now.
I looked at how the reception is on the floors and then wired accordingly - you could also calculate that, but I can't.
It's just the case that usually a central access point (or WLAN router) is not enough if you want good reception everywhere.
Better to have an additional network socket installed (have it installed) and not regret it afterwards.
We have a double socket in all rooms except the basement, pantry, kitchen, dining room, and bathrooms --> 12 connections. Three times is (currently) enough for us...
I have a can in every room. Plus a few cans for my speaker boxes. Then one just below the ceiling per hallway for wifi APs. I do the rest via wifi, as cables are impractical for mobile devices. Streaming and gaming over wifi is, however, just rubbish.