If you fellows would re-read what I wrote, I epoxy and reinforce with epoxy/Fiberglas the thin wall fittings to the Fiberglas wall. The piping in the wall is thoroughly strapped to framing and often foamed in place. To make a statement like “you have been using these wrong for years” is wrong and assaults me. Using drop ear Ellis only with no way to stabilize the tubing or pipe passing through the Fiberglas is ignoring the plain physics of the installation, relying on a “that’s the way we always did it “ logic.
If such an argument was true, we would still be using sweat fittings with solder fill holes drilled in them and “Orangeburg” sewer pipe.
By the way, your suggestion to use these thin wall fittings on stainless commercial sinks is not correct. Check any good copper fittings catalog for a “Sink Ell” made with an integral flange around the FIP tapping and 1/2” set inlet. Those are the correct fitting for the commercial sink.
Some research to determine the most recent best practices might be a good idea before attacking forum contributors in the future.