It's an organizational issue and has been for a very long time.
Young players are not given responsibility, even during the dark ages of 98-04. If the Rangers had drafted Ovechkin or Makar, the team would have insisted on not using them on the PP and forcing them to play the system and establish defensive reliability first. 5 years and 130 points later, both would have gone somewhere else.
Kreider bust onto the scene as a legit speedy power forward. What happened? Buried on the depth chart, in and out of the lineup. 10 years and a huge contract later, he finally has a breakout year.
Let's go back in time a little bit and look at all of the forwards that have busted with the Rangers or only reached their potential in other places:
Alexei Kovalev. Yes, he had his moments, but his points totals with the Rangers never lived up to everywhere else in his career. He should have been scoring 70+ points every year. At least we got Nedved back for him the first time. All everyone did was call him soft and an enigma, bench him for long shifts, and misuse him on the PP.
Christian Dube/Daniel Goneau. Aside from Goneau scoring at a hot pace to start his career, nothing. Dube never even really got an extended look in the NHL at all. A quarter of a season on the 4th line and that was it, and scored his first NHL goal in a blowout when he actually got thrown onto the powerplay.
Manny Malhotra. Besides being a headscratching pick, a guy touted as a potential power forward was never used in an offensive role. Aside from a quarter season at the end of 00-01 where he got to play with Messier, nothing offensively. And that was his third season in the league after barely playing in the NHL his second, after spending his entire rookie year with the big club. Turned into a defensive center which was no doubt partially influenced by how he was used.
Pavel Brendl - never played a game for the Rangers.
Jamie Lundmark - never saw ice time above the third line.
Hugh Jessiman - horrible pick. The Jason Bonsignore of his draft class. He even later said his heart wasn't in hockey. Team did NOT do their homework on this pick at all.
Lauri Korpikoski - another speedy skater used primarily in a defensive/penalty killing/grinder role his whole career. Jimmy Vesey before Jimmy Vesey.
JT Miller - In and out of the lineup, buried on the depth chart, not trusted on the PP. Gets traded right as he's becoming serviceable as a second liner and morphs into a top line player.
Pavel Buchnevich - couldn't earn ice time, he's too soft, blah blah blah. Then one promising season, and of course he's the odd man out for salary cap and has been a legit first line player since. Remember when it was obvious to every fan the KZB line was the best combo the Rangers had, and yet they still wouldn't use him there for another 18 months?
Lias Andersson - Drafted for "leadership" instead of skills, which made no sense at the time and still doesn't. Another stupid "defensive responsibility" pick in a forward at the top of a draft class.
Filip Chytil - certainly wouldn't call him a bust, but he was a high risk high reward prospect who has been underutilized. On the rare stretches he got to play with Panarin, he showed a lot - like he could be a 60 point guy someday under the right circumstances, but of course he never gets the chance (or wil get a concussion right as it looks like he's earned his big break). I still think he's far better than his numbers.
It's an organizational philosophy that kids have to earn everything and veterans don't. It's spreading your scoring instead of putting your best players together so they produce. It's Jimmy Vesey on the first line - which is something I said about why I wouldn't be thrilled if he made the team despite genrally playing well and earn it...because it took less than a month for him to be on the top line again.
And it's completely infuriating to watch season in and season out, no matter who the coach is.