Let's see.
Firstly, retail partners matter a ton. Even as we are moving towards a digital age, 50-60% of the business are still physical - give or take depending on the region, and until it reaches a point where the ROI isn't meaningful, partners who contribute 50-60% of your revenue are important.
Secondly, as previously expressed, the expectation and requirements for these kind of internal closed retail event are very different. Sony could bring nothing first-party or new to any of these events and it wouldn't even matter, because the ones attending DP are not people looking to be hyped by a new announcement, but business people who wants details that would allow them to plan their fiscal year allocations better. Whereas E3 ( or rather pre-E3 ) are driven by hype for megatons, new announcements, etc.
Thirdly, the success of sales and marketing is contributed by the full-stack and integration of above-the-line marketing ( TV ads, YouTube, magazines, influencer buys, Twitch, games press events, etc ) and below-the-line marketing ( point-of-sale material, store-level influencing, counter boys, pop-up events, local level events ). If we look at the consumer profile of a regular gamer, a lot of people are nowhere close to being a 'core gamer' who consumes all the latest trailers dropped at E3 and such. Many of them are casual gamers who's understanding of the closest product zeitgeist is brand names like Call of Duty, and there is an important aspect of point-of-sale marketing there.