I'm a strong believer in "path dependence" as a major influence in decision making by organizations and societies. All one has to do is read some business history to see this repeated again and again, if it controls major corporations, why should sports teams be immune?
That is, due to sunk costs and uncertainty, once an initial decision is made (aggressive reload instead of restarting the rebuild in 2018), it constrains future decisions until a dead end is reached and the decision makers are forced to move to a new path.
Part of the problem is that you often get positive affirmation that you've chosen the correct path (2019-20) before realizing you're lost in the thickets and brambles. Then the problem is your past decisions have limited your future options.
The reason I primarily blame Holmgren were three decisions:
1) not rebuilding after the Carter/Richards trades
2) hiring Hextall, but not giving him carte blanche (or at least encouragement ) to do a full rebuild
3) hiring Fletcher with a "win now" mandate
These three decisions determined the Flyers path from 2011 to 2025 or so.
Fletcher may not have made optimal decisions, but given the past decisions (that led to a paucity of top talent in the pipeline), and the mandate under which he was hired, no GM would have done much better.