It's true that the need for product liability protection begat improvements in quality control, including final assembly.

But the OP's bike shows no defects that I can see. If it were produced by a company that intended to stay in business (remember, many of the "fast-buck" opportunists of the bike boom years bought their bikes from reliable, experienced bike-building contractors), there would be some minimum of quality standards fully in effect, with only final assembly left in trust to the seller.

Certainly major bike-shop brands were not immune to defects like inadequate (for perhaps the first month of use) spoke tension or frame-joint inadequacy. I bought a new Trek once with serious frame misalignment, and a new Cannondale with unlined aero brake cables that caused a wipe-out mid-corner. A new DiamondBack Expert road bike lost seemingly all rear wheel spoke tension on the third ride!
I lack the data to say that department store bikes back then were of uniformly bad initial quality of the type that would fail even the disposable-bike crowd's expectations, and I suspect that some dealers worked hard to meet customer's expectations and avoid the dreaded call-backs. It is all a statistical game.

Of course, low-quality bikes are more of a challenge to work on, and the work isn't always reflected in even a half-decent service interval. Today's WalMart bikes suffer from such odd failures as hub cups working loose, which can make for a difficult shimming job. And or course the "suspension" components that they apply to boost sales are poor to the point of "why bother".
I actually think that the OP's bike, barring perhaps it's chromed rims and steel calipers, is possibly a better bike than what one might buy today at some stores.

And of course almost any bike is better than no bike.