The only SSD's I have are a 2.5" 120Gb SATA Sandisk I am using as a full Windows 7 backup (stored in a drawer; it will preserve the state of the system as it was when Windows 7 was no longer supported (fully updated)) for my Windows 7 Dell tower and the Intel M.2 660 SSD inside my Asus ROG Zephyrus G laptop. And neither one have I owned 3-5 years yet.
The point is not about age or lifespan decline, but value of the drive (as part of a system as a whole), when it CANNOT be replaced! How much is an M1 Mac going to be worth to you (as a buyer), when you have either no way of knowing how much life is left on the internal SSD (which CANNOT be replaced) or you know that a significant amount of it's life is used up?
Think of it this way... you're out to buy a used car. But the tires cannot be removed. Are you going to pay the same amount for that car with obviously worn tires, or tires that look like they're fairly new? I know it's a bad example (the car would have to have gotten very little driving), but it make sense, if you "go with the flow of the scenario" (which is "value for wear shown/known").