Maybe I misunderstand what you meant - but there were SMT components in 1989; indeed, some of the earliest examples of SMT can be found far earlier (late 1960s

Maybe I misunderstand what you meant - but there were SMT components in 1989; indeed, some of the earliest examples of SMT can be found far earlier (late 1960s for example). The reason it was likely thru-hole construction probably had more to do with reliability, as SMT work is more prone to damage from vibration (mainly), unless properly potted or conformal coated (and there may have been issues as to why they couldn't do that, either). That said, consumer-level use of SMT components didn't really start until the early 1990s - but examples of earlier use do exist (for instance, one of my floppy drives off my first computer in 1986-ish had SMT components on the controller board - but it was still mostly thru-hole construction).