Admittedly, I didn't watch that game. But even still I know Embiid didn't play every minute of that game, and not every minute he was on the court was 1 on 1 against Biyombo.

This was the same thing with that Ben Simmons vs Gobert quote, when it turned out someone actually researched it and almost all Simmons' points were when Gobert was off the court.

Embiid was -20 while Biyombo was +20.

Those numbers don't come from the contribution of just one player, and you know that. If Embiid was staggered with Maxey a lot then he had nobody else on his team doing any scoring, while giving up points, so it's obvious that he would have a negative +/- figure.