Sturgeon's Law: 90% of everything is crap.
In the end, the nomenclature is awkward, because "old school" means "traditionalist, with pride". It does not tell you what traditions.
QFT. Except that, with curation that no longer exists, about 70% didn't get shared, and now does.
We will chalk up the implication that creativity is somehow more the province of traditional D&D forms as a matter of poor wording, because it it were intentional, that would be insulting, and call for red text, which nobody wants.
Creativity is aided not by "old school" gaming in particular, but by breadth of perspective in gaming, by breaking out of your norms, and exposing you to new things. Modern players would be aided by doing a stint playing old school, and old school would likewise be aided by getting their heads out of the past, and into some new stuff.
From an educator standpoint, creativity requires a framework. Exactly how much of a framework is variable by individual. For some, the light scaffolds of Classic Traveller, Star Frontiers, D&D Basic, or Marvel Super Heroes provided plenty. For others, they weren't nearly enough.
AD&D was, for many, much better a framework than, say, Moldvay/Cook, as people carved down to the level they needed rather than adding framework to the level needed; the latter is itself a creative endeavor.
I appreciate the attempt! Of course, this is the internet, and by posting something, you will get those who disagree with what you wrote, those who disagree with you while ignoring what you wrote, and those who just want to argue ... because, hey, #winning.
When it comes to the older games (the first generation), it is interesting to look back at them and how I reacted to them at the time, as opposed to now. There was a period (we can call it the 80s) when I used to think that, for the most part, increasing rules density and expansion was the hallmark of good game design- after all, B/X was simple, and Advanced D&D was, well, Advanced. More stuff, more advanced.
I wanted to be ADVANCED! Who wants to be ... basic. YA BASIC!
And yet, looking back, I truly appreciate the simplicity of systems that people designed back then. Star Frontiers instead of Traveler - and my, the incredibly fast and simple Knight Hawks space battles.
Classic Traveller core isn't more complex than Star Frontiers AD+KH (which is the required to have the same functional modules of CGen, Personal Combat, Space Ships, ship combat)... Star Frontiers beats Traveller on consistency, not simplicity, since it has a single skill use mechanic.
Where Star Frontiers shines over Traveller, and D&D, and pretty much most everything else in print in 1982 is an easily grasped and mid-depth setting. Ignorable, if desired, there for those who need it. CT wasn't written for a setting; it was intended to be a Genre Engine, not the OTU game...
While Star Frontiers wasn't the first specified setting game (EPT, RuneQuest, Dallas, and James Bond all had specified setting), it was the first space-opera genre games with one. Traveller was morphing into the OTU game at the same time.
It's kind of a sad thing that the available fanspace for Traveller and Star Frontiers overlapped so much; Traveller had traction and Star Frontiers languished behind it.