Not sure if NeXT was a pioneer in those techniques, but they seemed standard by the late 1990s and 2000s.
Their golden days were during the first cellphone boom. Back then, the level of integration was lesser, and you had more discrete components on more smaller boards, and volumes were of course very high during the boom time.
Now, you can have a "dumphone" made with just 30 parts on the pcb, and very few passives.
From my experience over the decade, people running factories came to love having multiple, cheaper mounters, and more lines.
The "superboard" concept is also seem to be waning, as you see more, and more individual boards in products like smartphones. It makes for less manufacturable designs, but additional labour expense is not dramatic.
Early lights out production. The problem became obvious a little later, for NeXT, which was that these things only make sense at very high scale for products that change infrequently.