You can say it's the old boys limited managers fault. But there must be a reason why no young/ tactically efficient manager hasn't taken a punt aswel?
Probably not just a single reason. A few would be financial (their club can't/won't sanction his wages/fee), some would be needs (doesn't fit system/have better already), a few would be geographic/prestige (he's not going to go there/to a club that size) and some may be put off by his history (seems to fall out with everyone). Are there any young/tactically efficient managers you could name who wouldn't be put off by the first three reasons?
The part about the old boys club is spot on though. For reasons that we may never have the computing power to understand, falling out with Pardew has marked his career here for death.