This comment seems a bit speculative, do you have or is there information out there that supports this?
This is more anecdotal, but my time at a logistics company has shown the opposite to be true. Every cost increase, whether it was a tariff or increased fuel surcharge, was passed on to the next company, and to the next, down to the end consumer themselves. Every increase in vendor/supplier price was reflected almost immediately in the next invoice as our CFO instructed us to maintain our profit margins. There was even a multiplicative effect as each company applied their margins onto each price increase, such that a $100 increase in fuel costs could be double or triple that by the end.
It is possible that companies with massive margins might be willing to bite the bullet, but I doubt the advertising industry is full of companies with big margins. Perhaps the tech companies at the top, but definitely not the more numerous and smaller companies. For this reason, I find it extremely unlikely that "the end user will pay nothing". The end user will pay something, but the size of that "something" is certainly debatable.