German cars tend to be over-engineered; lots of modern tech in the vehicle + manufacturing, whereas American cars tend to be quite the opposite.
Think of the fourth-gen Toyota Supra or any version of the Nissan Skyline GT-R. Or the Toyota Soarer/Lexus SC, which was basically a detuned Supra packed with luxury equipment and unique styling. They were technological marvels whose engines were overengineered beasts that could take ridiculous amounts of abuse.
The Supra was a fundamentally ahead of its time design. Not without flaws but definitely pushing into new territory.
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).
The sheer number of Supras, Lexus IS300s (1st generation), and GS300s that are still running today, most with over 200k miles, is a testament to the amount of over-engineering that went into that engine.
And then there are the crazies who took the NA version and added turbos...
Sometimes I wonder if the US auto industry suffers a bit competitively vs Germany and Japan due to a higher amount of "brain drain" to other higher-paying forms of STEM jobs in tech.