Philly had Parent and Hextall for a few years and the unfortunate circumstances with Linberg but the rest of the time and especially in the last 2 decades, goaltending has been their downfall.
I think Philly has been blessed with pretty spectacular goaltending overall.
1967-71 they had Parent and Doug Favell, one of the best tandems in the league at the time behind Plante and Hall in St. Louis.
In '70-'71 they got rid of Parent and Favell became the starter until '73. Parent learned a lot from Jacques Plante in Toronto while Favell stagnated. '71-'72 in particular was a pretty bad year for the Flyers, missing the playoffs.
In 1973 they brought Parent back from the WHA, having acquired his NHL rights back from the Maple Leafs for Favell.
From '73 to '79 they had some of the best goaltending in the league.
In '78-'79 Wayne Stephenson had to take over from Parent and was a respectable 20-10-5 with two shutouts.
In '79-'80 they had a tandem of Pete Peeters and Phil Myre. Peeters outperformed Myre and became the starter in 1980; they dealt Myre away. Rick St. Croix became the backup but started most of the games in the '81 playoffs after Peeters went 2-1 with a 4.00 GAA against the Nordiques. St. Croix pushed the Flames to seven games in the semifinals but the Flyers lost the seventh game to Calgary 4-1.
Peeters couldn't stand being part of a revolving door in Philly and was dealt to Boston for Brad McCrimmon. Peeters went on to excel with the Bruins, winning the Vezina in his first season there. A lot of the blame for sub-par goaltending in those years can probably be put on the shoulders of Pat Quinn, who seemingly loved to rattle his goalies all the time. Keep in mind Peeters was still a damn good goalie: he played in the All-Star Game in '80 and '81.
Even after having botched the relationship with Peeters the Flyers still had great goaltending. A young swede named Pelle Lindbergh took over in Peeters' place and made it to the All-Star Game in '83, playing in tandem with Bob Froese. By '84-'85 Lindbergh asserted himself as the starter and won the Vezina Trophy.
He died in '85 and Bob Froese took over, winning a Jennings Trophy with backup Darren Jensen.
Froese was replaced in '86 with rookie Ron Hextall, who won a Vezina and a Smythe Trophy in a losing cause.
Hextall provided them with stable goaltending until 1992, when he was traded to the Nordiques as part of the Lindros deal. Admittedly Hextall could have been better, but the Flyers weren't exactly an elite team. He was quite injury-prone those years, and certainly not the sole reason they didn't make the playoffs in '90, '91 and '92. Bitter contract negotiations with Hextall in '89 couldn't have helped either.
Tommy Soderstrom and Dominic Roussel sure as hell didn't do any better over the following couple seasons.
When Hextall was reacquired in 1994 he was back in form and had some of the best seasons of his career.
In '98 they brought in John Vanbiesbrouck, who was definitely near the end of his career but was still quite good.
In 2000 Vanbiesbrouck was replaced by Roman Cechmanek, who finished second in Vezina voting and played in the All-Star Game. Admittedly he didn't play well in the 2001 playoffs but he was excellent in the regular seasons from 2000 to 2003 and definitely didn't deserve the blame he got for losing in the playoffs in 2002 and 2003.
Since then the Flyers nets have been tended by a revolving door including Robert Esche, Sean Burke, Jeff Hackett, Brian Boucher, Antero Niittymaki, Martin Biron, Mike Leighton, Brian Boucher
again and Sergei Bobrovsky.
If anything I think the Flyers goaltending can be best described as
mismanaged. Horribly mismanaged. From trading away Parent in '71 to alienating Peeters in the early '80s and trading away Hextall in '92 they've botched the relationship with every goalie they've had. Every goalie since Parent has (mostly unfairly) borne the brunt of the criticism for not having put them over the top.