I agree with the spirit of your post, as I think the depth of teams has increased greatly. I have no difficulty imagining the 2025 Blackhawks destroying the Gilbert Perreault Sabres (random example of a good team from the past) something like 15-2. Any fourth liner of today is a top-notch athlete in a remarkable shape, with fine tuned fundamentals, discipline and a solid knowledge of hockey systems and strategy. A fourth line of today could eat alive any line from the vintage era.
That said, the top talent will always compare. My argument for that is based on the most reliable measuring standard known to man : the Jagr-o-meter. Jaromir Jagr is the superstar player who played in both the early 90s and the late 2010s. He's been a clear bridge between that old generation and the present one. Would a prime Jagr dominate in today's game? I'd argue he'd contend for an Art Ross year in, year out. Maybe you don't agree. Imo he was always a beast. Well, as good as Jagr was in the 90s, there were still some 80s veterans playing during that time who directly faced Jagr on a rink and looked amazing too.
And those vets, they played against a still dominant 80s Larry Robinson, for example, who himself played his prime in the 70s with and against the stars of that time, and some looked as good or better than him. Emphasis on the word look. I know you said that some high-producing players of back then would suck today, that much is true, that's why I'm talking in terms of eye-test. Have you ever seen tapes of Bobby Orr? Train this guy from birth with the methods of today and heal his knees with the medical prowess of our time and he's a perennial Norris contender like Makar.
Back to Big Bird, it's not a stretch to say that a physical specimen with skill like him couldve been a great player if he had his prime in the 90s in an alternate universe. If he could do that, then a slightly older player could probably do it, and so on.
So, yes, today's players are just much better trained, prepared and fed than the pornstache era players, but the cream will always rise to the top, no matter the era. There's a limit at some point too. A player wouldnt score 10 a game. Well, maybe Ovie against the 1975 Caps. Lol.