The bladders have a limited life (just like belts, helmets, etc.)...any stamping with the mfg date on it has probably worn off.
Also...alcohol will kill the bladder, unless the bladder is specifically made to take it. Additives, octane boosters, ethanol...they well eat it.
there's no need to for the filler neck to have the webbing support since it's not really holding the fuel like the main bag (any topping off should be burned off quickly), and given the expectation that the cell bladder will be replaced on schedule.
My Butler got 20 years out of its bladder before it completely fell apart one weekend in 2002 after I threw a bunch of octane booster in for a track day. I got educated about the technology quickly after that...had to have Fuel Safe build me a custom bag to fit the weird can I had.
...which is ok since the handcut P7s from 82 starting chunking apart a month later.
Given all the crap they're putting in pump gas, unless you're racing...spend the money for a tin can and don't stop short on anyone behind you.
...just sayin
