You're not looking at this the right way. Cutting down the current NHL to a 6 team league would NOT leave you with a similar level of competition to the early original 6 era NHL.
What you'd be doing now would be cutting down a larger, more talented talent pool to come up with 6 teams. The Original 6 wasn't drawing from such a developed and talented pool of players. There were less players playing hockey back then and less feeder teams, not to mention lesser training, conditioning and coaching.
I also think you are diminishing how many talented players there are today. Let's look at goal scorers. Over the 3 seasons prior to this one, I took the Top 10 goal scorers from the last 3 seasons from nhl.com’s lists and you want to know how many players appeared on each list? The answer is only 3 players were Top 10 goal scorers for 3 seasons in a row: Stamkos, Couture and Toews. Only 3 players were top 10 in 2 of the 3 seasons – Carter, Staal and Tavares. 15 other players made the Top 10 at least 1 time in 3 years.
When you have a bigger sample size, the top end talent group will be bigger, as will the lowest level, and the biggest group will be the middle level. That happens with any decent sample size.
As for Gordie Howe, if he had to play 82 game seasons and marathon playoff runs, like players do today, he might not have played as long as he did. Regardless, I don't agree that he'd be playing against weaker competition. Let me put it this way, if Howe's team were playing the Bruins he’d be staring at Chara every time he was on the ice. Teams wouldn’t be playing their bottom D pairs or scrub fourth lines against the likes of Howe, he’d most likely be facing top defensive competition, or trying to contain top offensive counterparts on a nightly basis.
Fine, I'll look at it your way, in which case you'll see almost identical diversity of scoring. Your bolded example doesn't prove much difference between now and then, as the statistical numbers are almost identical when Hextal played. The two years Hextal led in goals, and the season after where he was second in goals, there were only 3 guys who were top 10 in goals all three years (Bryan Hextall, Gordie Drillon, Roy Conacher), only 4 players who were top 10 in two of the three years (Bobby Bauer, Sweeney Schriner, Lynn Patrick, Woody Dumart), and 16 other players made the top 10 only one time in those 3 years. There is essentially the identical level of diversity in scoring, except Bryan Hextall is 1, 1, 2 in goals those three seasons, led the league in assists one season, and was 6th, 2nd and 1st in pts. That's pretty friggin dominant, in a nearly identical diverse pool of goal scorers as the example you just cited. Not to mention Hextall won a Cup in that stretch and led the Rangers in playoff goals that season.
Regarding Gordie Howe, I think you are seriously underestimating him and just how durable and how exceptional he was. For one thing, almost his entire career was 70 game seasons and he barely missed any games. I don't think an extra 12 games a season would have affected him in the least other than him tacking another 200 points to his career totals. Secondly, regardless of era, he still played more NHL regular season games than any other player in NHL history and he played 157 career playoff games. Only Mark Messier has played more NHL career regular season plus playoff games than Gordie Howe. He played a ton of NHL hockey, second most in NHL history, and that was with him playing 6 seasons in the WHA before he returned to the NHL. Then there are the 22 consecutive seasons over 20 goals; 18 70-game seasons where he was over 70 points; and a 44 goal, 59 assist, 103 point season
at age 41. Lastly, and this to me is still one of the most insane achievements in NHL history, but he actually played 80 games and scored 41 points in his final NHL season,
and he was 52 years old!
The man scored over 100 points in his 40s, and then played 80 games and scored 41 points in his 50s. FFS three fourths of our team can't even hit 40 points and he did it at age 52 lol. The dude was a beast and a very credible argument for the greatest player of all time, totally deserving of the title Mr Hockey. And if you ever meet him in person, one of the most unassuming down to earth people you'll ever encounter. I met him at a card show in the 80s and wanted him to sign a painting I did. He couldn't sign it because of contractual issues and having some agent present or something. Mr Howe felt bad about this, and he actually gave me his home address in Hartford and told me to mail the painting to him. He said he'd sign it and mail it back. He did that and sent me 5 signed 8x10s, too. Class act all the way and an absolute dominant force on the ice.