It's certainly a time saver. :^)
I've met people who do that because they can concentrate their time on detailing & painting rolling stock & locomotives. They had a nice club layout all scenicked that they can operate on when they wanted to. Common denominator among those guys was that they just wanted to build & run trains.
The first layout I ever saw, I was 5 yo and it was a friend of the family who had it. That was 1973. I remember the tracks (HO scale) going through holes made in all the walls in the rooms in the basement. It went everywhere & he had a small yard, all undecorated & unballasted. I revisted in 1991 and it was still the same.
A friend in 1992 had an HO double track going around the perimeter of his developed basement, it also had a staging yard. No switching opportunities at all... just trains going around & around. No scenery or anything. Oh he had big plans for the dream layout & he certainly had the space for it but he never got around to it as he belonged to a couple of clubs & also dabbled in G-scale. Too busy I guess. He did build a decent sized yard by 1999. Unfortunately he passed away in 2007.
Personally, I prefer scenicked layouts with detailed trackside structures like switch stands, telegraph poles with wires, working signals, phone boxes, etc & bridges.