There are a couple of things that make me think twice before I agree with that. First, in the 70's, nearly all bass that were caught were kept. That means the only fish left in a lake to reproduce had the disposition of being more difficult to catch. Now with the popularity of catch & release, the most gullible bass can get caught 30 times, yet still end up with old age being his cause of death. Having those willing to bite fish in the gene pool seems as if it may balance out the increased angling pressure.
Second, the plastic worms of today are a far cry from the Crème worms & Mann's jelly worms of the 1970's. I remember the first time I saw a Mister Twister worm with a 4" curly tail, I thought that I would catch every fish in my lake. With the addition of scent, specialized hooks, softer worms that the fish hang onto, tungsten sinkers and more sensitive line & equipment, catching a bass with a 6" plastic worm is much easier now. Remember how good you used to have to be to even feel a strike with a fiberglass rod, monofilament and a lead sinker?
I may be swayed by personal experience on this. I added up some totals for 2014 from my fish logs & over 1/3 of my bass were caught on T-rigged plastics, with another 1/3 caught on wacky rigged Senkos. Some of that may be experience I have gained over the years, but it sure seems like using plastic worms now (& catching bass) is much easier than it was 40 years ago.