Couts and Giroux aren't generational players, at least not as I think Xogfog is defining them, or at least not as I would. You'd be talking like, the 3-5 best players in the entire league over a 15-period. Multiple Hart winners. Surefire Hall of Famers. Not just great players/All-Stars. And of course Cup winners, though part of this discussion is that not every generational player gets a good enough team around him (including McDavid and Matthews).
Great Flyer though he was Giroux was at best the fifth-best player in the division of his era (Crosby and Malkin, Ovechkin, Lundvquist) and you could still debate that with a few other guys (including a few defensemen and Fleury). And he definitely could have used a #2 like the Pens and Blackhawks had (even the Caps had Backstrom). In the Flyers' case that could have been Pronger and should have been any number of other guys, but, it didn't happen.
As in other sports, tanking sometimes works (Astros, Cubs, Penguins, Blackhawks, Cavs, Spurs early on) and then a bunch of other teams try it and it doesn't work out quite the same because there's also luck and good management involved.
As for the bigger question I'm not sure you guys actually disagree on anything. Yeah I think they can be competitive and have a foundation in three years but it will take five to finish the job. But this past season was their best shot at landing a generational or even elite player. Whether or not to trade someone like Tippett is probably besides the point. They would really need to trade Hart and a few other guys (including Couts if he's healthy enough for someone to take him) to be seriously rebuilding.
Flyers have hardly been alone in this. The Red Wings and Devils became irrelevant forever. The Islanders got nothing out of the Tavares era.
On the other hand the Dallas Stars made the Cup final (albeit somewhat unexpectedly) with a core built around two long-ago fifth rounders (Benn and Klingberg) and the start of the current core out of a single 2017 draft (Heiskanen/Robertson/Oettinger first two rounds).