I think the cases where Early Access could technically be considered as...well, a proper EARLY Access, would be mainly if not exclusively with indie games that have yet more content to create and presentation polish to add, but still are launched for players to finally take a shot at it, give them a fair slice of what's done currently while there's more planned to come later [in the ideal scenarios], and when the full game launches, anyone that bought Early Access would be able to see the proper full launch of the game with the stuff that was promised...free of charge.
And that's because if you bought Early Access, you basically already bought the game- so you get the right to the full thing when it's out.
I know this at least from a few examples, such as BallisticNG being in free Early Access years ago when it was still quite on the smaller size and on development [and I got it] then could later on see the full priced launch and big changes while still having my copy at hand, and Aero GPX which not too long ago launched in Early Access and likely will get a full launch near the end of the year if not at the start of the next one with more content...but currently does have fifteen tracks and around ten vehicles, so there is at least quite something there already that you could grab for cheap and then enjoy a bigger version without re-buying the game at a higher price tag.
For AAA games though, I get how often there's always a chance of there being a slippery robbery- mainly if the only incentive there is for Early Access is getting some preorder bonus or such [rip Fallout 76 early adopters waiting for their canvas bag].
Early Access such as Steam Early Access I can get behind. I'll be making a post about that sometime in the future! But my main gripe is the "early access" to already full games.