I wonder why the issue can't be reversed after the drive has gone read-only. Faulty cell integrity reporting, perhaps?
Results of reverse engineering performed on older Samsung models revealed problems with the NAND flash itself. As consumer models often get some of the worst binned NAND (despite their "premium" pricing), the firmware is critically important to ensure NAND writes are carefully managed to avoid irreversible damage/wear. The problems are always there, but they are rarely revealed in a meaningful way through SMART.
As long as the drive can operate up to its rated workload level, then that is the goal regardless of the questionable quality of the raw hardware underneath.
If it turns out to be a similar issue with these models (980 PRO and 990 PRO), then if the damage has already been done it would be too late for a firmware fix. Alternatively, Samsung may choose to hide the underlying issues if the drive is still salvageable - and no one would ever know.
As usual, this is occuring due to the secretive locked down nature of the firmware which Samsung don't even provide proper changelogs for. Thankfully, some work is being done on reverse engineering these - but there is little incentive for those with the skills to dedicate the time with no compensation.
In any case, it's only a matter of time before discoveries are made outside of the Samsung "vault" so people can make more informed buying decisions, which can only be a good thing.