Two issues with that.
One, being a cumulative progress based game genre, as a game company you might have to handle the situation by resetting all progress Early Access users made so far due to a simple game breaking bug seeping into the game. I’m not talking about expected lag issues, graphical glitches, slow render performance, random disconnects, bad hit register and collision checks and so on, those are expected problems on a day zero release of a new game with a crowded studio.
I’m talking about bugs that can be exploited, allowing a single individual having a huge advantage by finding out about a loop in the code. There’s a difference between gameplay issues due technical problems and game breaking bugs that threaten game integrity of a multiplayer game. When that glitch carries over by progress, company obliged to check every involved players’ account to reverse the changes or reset things at the end of Early Access phase. That’s tiring and not worth the risk at all.
Two, since Early Access will not be as stable as a full release some people will wait to buy it anyway and this won’t be reflected on your stock market rise fully. Even though the game has a huge advertisement campaign and hype surrounding it, some players will be cautious to tread instead of pre-ordering mindlessly.
However, since you practically released the game, investors will ask why your stock market haven’t risen properly. Being an early access, company still have to send out advertisement campaigns continuously to remind you of game’s presence along it, hoping players would get it at full release. That’s also extra cost.