I think your understanding is correct and well documented.
I am quite dissappointed to realize that consumer drives do use dynamic leveling, which, in my opinion, is sh*t. I would rather my writes, which are already slow(er), degrade in the background to wear the whole drive evenly and maintain capacity throughout the life of the drive.
However I think that a real-world use case investigation would show that even with dynamic wear leveling, things are not quite as bad as they seem because, with the operating system running, probably more sectors than we think are being written on a regular basis, thus more of the drive than we think is being used for wear leveling. Only completely static files (images, music, etc.) would never be touched. So if you filled the drive up with photos, maybe you are right and the flash media would degrade in the worst way possible, which is part of the drive reaching end-of-life prematurely, essentially reducing your capacity and shrinking your drive.
Bad times...
EDIT:
doing a little math:
My WD Blue 250GB SSD is rated at 100 TBW (Tera-Bytes Written)
This means it should support ~55GB of data written per day, assuming a 5 year warranty period.
It also suggest that the cell edurance is 400 cycles.
I think this is on par with most other drives.