My Grandfather owned a fuel delivery business with gasoline powered trucks and told me that from the 50's back, stuck ring packs were almost always the death of an engine. When the ring packs would stick, they would start using copious amounts of oil and the end was near. He almost never made it to 100,000 miles on a truck back then.
Not sure, but it is possible. My point was - it doesn't take much to have that amount of buildup. On some engines, using "approved" oils and following the maintenance schedule will have it looking that nasty.
I would argue that before fuel injection, or even the early years of fuel injection, we were seeing engines that looked this bad on a daily basis. It was normal. And it was also normal that most were considered “done” a little past 100,000 miles. Those are my memories of working on cars in the 80’s.
And as much as we complain about cars/engines today, they’ve come a long long way.