Duck Duck Go clearly think there is profit in contextual ads - and I would love to find out if there is any hard evidence out there either way?
(other than the obvious Google and FB do personalised because it is more profitable. I know that and at FB scale a 1% profit improvement is worthwhile pursuit - but from society's POV that 1% diff may as well be irrelevant- it won't improve the mom and pop store bottom line enough for the damage it does.