Well, it's not only relevant to marketers. Your two most innocent examples are not the only type of information that's going to slip in there.
And even with those two examples, you just have to be creative to find ways for them to damage you:
You'll probably have to pay more for your health insurance, if they find out that you enjoy motorcycles.
And if your next potential employer is vegetarian, they might pass on you for fishing, a.k.a. killing things as a hobby.
Someone wanting to rob/extort/kidnap/murder you, might look for you at lonely lakes in the region.
And these are the most generic examples of this supposedly useless information being used against a person.
Someone who happens to have an actual use, is going to be even more creative, since they'll find themselves in some particular situation where it's useful.
And again, there's going to be more information. They can sift through an entire list to find the ones that are useful and they can combine multiple pieces of information, too.