crank shaft seal dislodged and leaking oil on 2003 Hyundai Elantra

What would cause this

Asked by for the 2003 Hyundai Elantra
Excess crankcase pressure due to a restricted PCV valve could cause this or a kinked or restricted PCV hose. if the engine crank "breath" it will develop pressure internally and cause several engine oil leaks. Could the seal just got hard and brittle due to age?