While the technology continues to improve, the fact is that flash memory has a limited number of times it can be written to. It can, in fact, wear out.
I see the appeal of slipping a little SD card into the slot of your computer for backups, but the safety of your precious data on that card has me worried!
Constantly writing to an SD card will shorten its life. The question is how much? That’s going to depend on several factors.