Yeah, shares as long time investment for big companies are rare thing these days. Most of trade is automated gaining/losing on huge amounts to gain difference of margins, and that's how most profit these days are getting made. Yes, there are long term investment funds, and those won't jump from EA, or any other big company because of E3 or something else really. And PR become a thing with these automated/short sellers. They tend to dictate how market behaves and yeah, it is nonsense.
Also in last few weeks market finally corrected itself after huge cashout as ride to green pastures ends around the world, and recession is around the corner. EA and Activision both still racking huge amounts of money via MT, so no, gamers have done very little to influence behaviours of these companies, quite the opposite. They have mostly confirmed that gamers will buy anything with big franchise name attached to it, will suffer MT in single player game at ease, and even will accept lootboxes if they have to.