Yes, that is the same argument on both sides. If a copper fitting fails, the copper guys says it's due to a faulty installation, and if the Sharkbite fitting fails, it's due to the nature of the fitting itself. If a Sharkbite fitting fails, the Sharkbite guy says it's due to a faulty installation, and if the copper fitting fails, it's due to the nature of the fitting itself. We've heard all this ad nauseum.
I've seen plenty of copper fittings and pipe fail due to acidity in the water. I've also seen high zinc content PEX fittings corrode and fail due to dezincification. Presenting just one side of this argument makes anyone sound like a lawyer, and uneducated about both sides of the issue.
Somewhat misleading to say that chlorine breaks down rubber, when Sharkbite fittings are made with EPDM which is not a real rubber. It is not natural rubber, it is not isoprene, it is not nitrile, all of which have poorer chlorine resistance than EPDM.