It can be cheaper, on a cost per acquisition basis, to buy a company that has customers who could also be interested in buying your product. That thesis has driven a lot of small M&A, not just in Europe but around the world.
With GDPR just around the corner, I'm sure like me you've been asked to renew your opt-ins for many email newsletters. I like it for the same reason I like when my credit card expires: it feels nice to be asked once in a while. And to be able to reset all that stuff.
But if that a new opt-in needs to happen when you buy a company, and the conversion rate of consumers opting in again is low (30%? 50%?), you won't be able to move a lot of the customers over. And consequently the math stops working for a lot of the smaller M&A transactions that work on the customer acquisition logic.
I'm sure there are lawyers working on this. Maybe it's not a real, real problem. Maybe there's a way to stay compliant (we're advising all our companies to err on the side of caution). But I've now heard it mentioned several times so thought I'd flag it here.