I have a different perspective. Most of the turnovers I have seen are voluntary - people moving on to different companies, different roles. So to me it's not necessarily a bad thing. Personally I get bored doing the same thing for more than 2 years. So if my role does not present new learning opportunities, I will probably move on.
On the other hand, in general marketing can be an easy culprit when business is not doing well and budget needs to get slashed. It's just the reality of the profession.