I have no data to back this up, but my gut tells me it happens a lot more at companies where the CEO isn't a founder, or doesn't have a high degree of ownership.Agreed, once the original vision is gone something else takes its place and it is just a ghost of what it was.
This goes hand in hand with the owners/founders being more focused on product development, engineering and innovation. Engineering and innovation are costly when marketing or bizdev/accounting/metrics runs your company which typically happens when the founder leaves. Engineering takes a back seat to decision making, marketing tries to pump revenue out of a product that may be successful not but is not being iterated or innovated on, or the next big thing is not worked on because the company is fat and happy until the grace from that innovation runs out. People join during times of success to latch on and cash out, when the hard work of innovating comes along, those people are gone.
Companies like Amazon, Apple, Google win because they are willing to take innovative risks, engineering is not in the back seat but a driving force and they invest most of their profits back into more innovation, Amazon is probably the best out there at this. Microsoft used to be as well and is coming back a bit but they fell into the trap above when Ballmer took over for a while, more focused on revenues and metrics than the next big step which will always put the current players out of business, or missing a step, if they don't adapt.