Well… this happens when Companies are run just on short-term fiscal numbers and expectations and not long-term values, assets and technologies. Bought Managers from outside sometimes are like Birds of Prey, they come in, optimize everything for Shareholders-Short-Time-Value, get Millions of Boni and quickly move on before things getting worse.
Nokia’s problem was not innovation - they had a lot of patents and devices prior the iPhone. The problem was the Management. In germany we have a saying for this: “Der Fisch fngt vom Kopf an zu stinken” - translated “a fish starts to stink from the head”