I'm not opposed to going the other way, if Level up wants that. I just don't think it can stay as is with classes balanced around a ratio of short rests to long rests if we're going to leave it up to the DM to make something close to that ratio happen. Your class's baseline effectiveness shouldn't be basically up to the DM's whims or how many encounters per day your party or GM finds annoying. If we can rebalance the classes so they all want long and short rests, or so that they all only work off only long or short rests, then the rest system doesn't need to change. Otherwise, we gotta do something with the rest system.
As far as something in the opposite direction from a metagame rule, removing the easy availability of long rests might be an option. Every time you sleep for 8 hours probably shouldn't cause a long rest. You should need to find somewhere a little more comfortable to get those benefits. Exhaustion would still enforce sleeping every day, so that's not too much of an issue.
This would at least make it so the GM doesn't need to provide 6 encounters a day to make the short rest classes equal to the long rest classes. Even if the GM only has 1 encounter a day, they can make long rests weekly-ish by not providing comfortable sleeping locations in the area, or adjust based on how safe you want the long rest players feeling. Now we need to keep in mind that this system relies very heavily on the GM being careful about when they provide long rests, but if that's made clear in the DMG equivalent, that's probably fine.
It's better than the current system, because very few situations call for 6 combat encounters a day. It's pretty much just dungeons where that makes sense. This at least openly tells the GM that how effective classes are compared to one another is up to them. And GMs need to know that that's what rests are doing mechanically, because I think a lot of GMs don't even notice how heavily their current rest structure favors long rest characters.