id agree with you if it they left it to organic traffic to find/buy Shenmue 3 on the Epic store. However, Epic's video ad of Shenmue 3 has over 7 million views in 7 days. If only 1% converted into buyers, that would be 70k copies sold, 2%, 140k copies sold, etc. Average conversion rates for ads are usually 1 - 2%. Although i have no idea what it would be for video games in the holiday season.
7 million views on an ad would cost crap ton of money. I know from my own experience in marketing that if a video ad is not making you money back from selling the product, you would kill the ad or stop it immediately. This shenmue 3 ad continues to go up at a insane pace. A good example of what i mean can be seen on Deep silver's youtube page. Looks like they made all their Shenmue 3 videos into ads but stopped some of them half way through, which then stagnated the views, while they let others continue, presumably because they were making money back from sales on those continued ads.
The funny thing is, i've never seen Epic push any of their exclusives like this. Makes me wonder what was in the agreed deal. You'd have to assume marketing was a massive part of it and it would probably explain why they were advertising Shenmue 3 at E3. Personally i think Epic are using Shenmue 3 as an experiment. If they can market the game and make it successful, im sure they'll start to offer similar deals to new potential developers/studios, and that along with the money and secured sold copies would be an offer no one could ever turn down.