He's right.
Today, a 140 character tweet has a larger reach than a trade show press conference that costs $3million to put together, requires 24 people to fly half way across the world, permits, security detail, scheduling, and dozens of other high-cost, low-return requirements. Heavy weights in the industry have shunted trade show press conferences because they don't need them. 10, 15, and 20 years ago trade show press conferences made sense because it was too expensive and difficult to get coverage for a lesser known game, so studios would band together to "show everything" to a collection of press corps all at once. For the press, it made sense because flying your journalists to a game studio to see one or two games was costly, but putting them up in a hotel for 4 days in Los Angeles to see 300 games being released in the next 6 months was cost effective... They'd get 6 months worth of magazine or website content in 4 days, covering the entire industry.
There's no need for this anymore. Developers and publishers go straight to their fans with announcements. Rockstar has been doing this for years, since around 2007 at least, where the first reveal of GTAIV was done on their website, promoted via an email. With GTAV, they continued this and only expanded on it. Almost all of the promotion for GTAV was done through email, twitter, facebook, and other forms of inhouse marketing. GTAV is the fourth biggest selling game of all time and has made Rockstar billions, while their convention budget was effectively nil.
For the press, flying someone to LA for four nights is expensive and does not have a strong return. Gaming press make as much money on a 60-minute YouTube video reacting to other YouTube videos than they do writing 800 words about a game that they got a hands on with. Developers and publishers are less willing to offer hands on at shows like E3 because they can't control the gameplay. If they're going to offer a hands on, it's like what EA does at EAPlay, which is in a controlled environment that they can ensure only specific parts of the game are revealed to the public. This makes it less cost effective for journalists to go to big press events, where they get crummy coverage of a game that other people are getting better coverage for at home.
Other companies like Valve and Nintendo, two of the biggest names in gaming, have largely abandoned trade show press conferences as well.
Now, it makes a lot more sense to wait a week or a month after the big industry show and reveal your game on your own schedule, without setting up a conference booth, and without taking direct interviews. It allows the publisher or developer to craft the story about their game in their own setting, under their own guidelines, without the need to have to "wow" a crowd or have bad optics of people not paying attention to their title or stream commenters shout "BORING!" in a chat.