Yeah it's probably fair to say that it was harder to qualify back then but easier to win. Alternatively, there was no group stage back then so one bad night (or two) and you were out. Though that's true now too when we get to the knockout rounds.
One thing I will say is that names that look like diddies now were pretty handy back then (though you could meet literal amateur teams too) Teams like St Etienne, Steaua Bucharest and Forest (who only recently got back to PL level again) were really strong. It's like the idiots amazed that Aberdeen beat Real Madrid and wanking over Purple Nose - back then Aberdeen were miles better than they are now, and Real Madrid were much worse. The gap between teams was much smaller before the satellite TV, internet and capitalist revolution. If you look at some of the teams that won European trophies back then, they're non-entities on the European stage now but were strong back then. We shouldn't look at such teams now through the prism of the present.