>>1984903they had triples, even occasionally in the pro tour.
Giovanni Battaglin won the 1981 Giro on pic rel
Triples were reasonably common on nice road bikes all through the 80s and 90s.
53/42/30 type thing.
The compact and subcompact double also did exist back in the day, mostly french equipment, i have a stronglight 48/32 that is around 40 years old.
Less exotic, SR and Sugino 110bcd doubles were pretty common, but oddly they always seem to just have std chainring sizes (52/42 etc), not compact rings.
As for why tight cassettes, yes, gaps in gearing, also, for older stuff, freewheels often had a small wobble, you weren't getting modern ramping on the cogs for shifting, and the derailers of old were much worse than they are now and sat further away from the cogs. It just wasn't desirable to mess up shifting when a close block and a short cage derailer is just inherently much smoother.
The shift on a std double is also butter compared to going across a bigger range, and the shift patterns of old involved more front shifting and less cross chaining, the small chainring wasn't a bailout, you spent more time in it rather than escaping down the rear block in the big ring.