This is technically true but it sorta misses the forest for the trees.
Ideally, in a world where covid hasn't ravaged public events, E3 exists as a marketing event that brings publishers, game developers, reporters and fans together to experience and see upcoming games and hardware in a festival setting.
Like, no shit, it's better and easier for publishers to just put up a video online, promote their shit in the most optimally curated manner and call it a day. But, is that really the only metric to judge this on? I frankly don't care about that. I'd rather have a hands on experience that allows people/reviewers/etc to actually see the goods first hand. It's more meaningful than just having some corporate person post a video that's just a sales piece to get you hyped and then be done.
People really seem to forget or miss the point of what E3 was about. When they closed themselves to the public, fans were outraged and that ironically begun their slide towards irrelevance. The fact this year there were so few publishers, and those that showed up had so little to show, had more to do with E3's lackluster showing than anything else and that's the reality of it. It's going to be a sad day when there are basically no public events that bring gaming to the masses. Japan sees value in such event promotion, it's a shame a lot of other places do not.
Yeah, E3 sucks but once it's dead, there's not going to be anything else to take it's place and gaming won't have an event that publishers will have any desire whatsoever to participate in for the sake of the public. Then we can all just silo ourselves to our direct corporation, become excited for product, and then consume product. Efficiently