Yeah, I was considering trad rules design to be what grew out of that playstyle once the published rules started reflecting what was already a playstyle. E.g Dragonlance shows us a trad trajectory, but 3e was probably when the rules were really designed around it.
Characters become more durable so you're less likely to lose a character (which lends itself to stories that now have consistent casts), players can take all sorts of rules options that both make it easier to just kill team monster (power fantasy, combat as sport) and customize your character (self expression, built to last).
In classic, characters were rolled and had few build choices (less self expression, no one cares what you 'want' to play, streamlined character generation because death is a regular part of play) they dont have much combat capability and are expected to encounter things they can't handle (fair fight as failure state, 'oh crap run' as an alternative OSR acronym) and so forth...
So its easy to see what adaptations came out of the trad playstyle as a result of classic, so its a matter of identifying the maladaptions that locked off certain elements, and approach the problem with an eye for solving it for the specific principles.
It probably is something new (or at least a self conscious variety of neo trad) but to me its fairly definitively rooted in frustrations with the borders between OSR/Neotrad.
Im probably not alone in seeking out that new space either, id actually go so far as to say its a neo trad impulse toward character stories and self expression (my origin story, hilariously, is the canon neo trad one from six cultures of play) that aren't submissive to a main plot, realizing the possibility space of how OSR adventure structure can provide that.
Specifically, OSR modules often provide scenarios for players to engage with and explore, without demanding they step into a main plot-- in Barrowmaze, for instance, we're literally just given a space with many mini dungeons, and one large complex.
There's no plot, it just gets more dangerous and more lucrative as you travel from east to west. There are climactic bosses for the campaign, but encountering them is a consequence of choosing to explore the Barrowmaze enough that you run into its lore, origins, and big names.
To me whats cool about that, is that it puts the players in the drivers seat. The module doesn't walk you through a sequence of specific events for plot, so it feels more authentic. It also centers the relationships of the player cast for the roleplaying that does take place, and doesnt impose on your sense of driving possible drama and roleplay in the same way that Story Now 'play to find out what happens' might.
From a neotrad perspective, thats really cool, and the centering of the fictional world 'lore' rather than plot provides a comfortable escape from the tension between trad and neo trad (THE storY vs. OUR storIES) you have more room to express yourself in the naturally emerging story of the OSR.
But obviously, losing characters so easily undercuts that, sublimating your character self expression to focus on hard-core survival tactics (to the exclusion of all else) undermines that, rolled characters who you don't customize much and are likely to die to one wrong move undermine that. So the question becomes how to get what I like from the OSR, without trading away these other things we enjoy playing the game for.