Until the separate subforum for a certain category is made and tried... one will never know what's the better method.
Yes, there have been and will be times where 3rd party stuff that gets posted within the "current D&D" subforum finds their threads bumped from the first page quickly because no one posts in it fast enough to keep it on the front page.
Likewise, there have been and will be times where a separate subforum is created for some variant game version that finds themselves getting barely any traffic, which results in few threads being engaged with, which results in people who show up to it to engage seeing that the subforum is pretty much dead, and they then choose not to engage with it (killing the subforum further).
Both things happen. And how any particular game variant version would behave in either method is unknown until one of the methods is tried.
So whether or not an entirely new "5E" subforum is made to encapsulate any 3PP games based off of the 5E SRD and not based off of the 2024E game... or if those games should either just fall within the "D&D Older Editions" subforum, or get grouped within the "Level Up" subforum (to become a 3rd Party 5E subforum)... we'll just have to see what Morrus decides to do.