Trust me, people in the pedal-making industry know exactly how much influence those interviews have, and that's why they put so much effort into making those artists happy.
They don't make them "as happy" as you might imagine. Even a guitarist that is good enough to do European tours and get an endorsement deal will get discounts of 20% (on pretty expensive stuff for which they would have to fork out 2000 euros), maybe 30% on bespoke instruments that cost even more.
I'm not imagining, but a 20% endorsement deal and (in the cases I know about) a much more direct line to an artist rep for customer support in lieu of going through the customer support process isn't too bad.
Hell, I've gone to shows for the sole purpose of hand-delivering the artist a replacement product.