Jadnashua
Retired Defense Industry Engineer xxx
Many of the o-rings in faucets and valves need to slide or rotate. In a sharkbite, once it is installed, it's stationary, so it should be pretty long-term. Neoprene as used in a no-hub seems to last a very long time, and the o-ring is probably similar. deriding them out of hand is your right, but may be unfounded. Testing says they last. Improper installation can damage them and could either cause them to fail on install, or early.