If she were physically equal to Superman, she'd make him redundant, considering she's much more skilled, magical, with a sword that cuts through anything, with a bracelet that blocks anything, and with a lasso that bounds everybody.
She also has no weakness, compared to kryptonite, red sun and magic.
Give her a GL ring (I'm pretty sure you'd say her willpower should be high enough to handle one), and the Justice League can go on vacation.
She has never been as strong as Superman. This is consistent, among the entire comic book publishing history, to the point where I'm honestly amazed a small amount people still exist that cling to their internalized fan-fiction. It doesn't matter what writers say, Gladiator was created to be Pre-Crisis Superman, Thor was created to be stronger than Hulk, and much more, what matters is what's published, not what writers say in interviews to stroke egos.
You're going into 'secret collusion' paranoia that is, quite frankly, embarrassing.
She's a badass warrior, with OP weapons, tactical ability, fighting ability second to none and physical ability second ONLY to Superman, who has none of the former. The longer you continue this inferiority-complex based "but she also has to be as strong!!!", the more people will face palm.
Doomsday is a physically nigh-unstoppable being, which makes him tailor made for Superman. Wonder Woman losing to him, when that's not her strength, is not bad. The same way Superman losing to Circe, while Wonder Woman beats her, is not bad for him.