Because playing decent chess +99.9% of the time is enough to hide its weaknesses. If NNs see some moves that AB engines simply don't see or won't play and they're best, in those positions SF is playing really weak chess. What happens in analysis after the game has been played doesn't matter, just like "best play" doesn't matter, and what matters is the moves that are played when a game is actually happening.
If I'm playing a game against you, jp (let's make this personal), and I play a move suggested by a NN, and you miss it because you only used Stockfish, and I beat you because of that, it doesn't matter if afterwards you analyze the position and claim that the move I played wasn't better than the others, that the actual score is 0.00, that Stockfish was right and that it's a draw with best play, because I already beat you.
That's how chess is like, it's about making the opponent blunder in a drawn position, if it's more likely than not the evaluation should reflect that, but it makes no sense to show scores near 0.00 because it's a drawn position.