They did indeed, which matches the comics where Thanos doesn't need a stone to beat Hulk there.
People always forget that Hulk is the strongest, but he has to get increasingly angry to get there. Thor is as strong baseline as Hulk is, but, as the fight persists, Hulk gets stronger and stronger. Look at the Hulk buster fight. IM is handling himself pretty well, then Hulk starts tearing him apart like paper. It's only after Iron Man brings own an entire building on top of him that the spell is broken, he's no longer as angry, and Hulkbuster, no longer holding back, KO's him. However, when he was mad raging, he was unstoppable. Hulk fought Thanos, and, when he didn't immediately win, he panicked, and didn't get angry, he got scared. That is why he lost.
Angry Hulk= Unstoppable rage beast.
Scared Hulk= the Child Bruce Banner is inside, who just wants to run and hide.
Pretty simple. Are people still torn up about that Thanos beat-down from over a year ago? Sheesh. Also, for those wishing Hulk would have gotten some retribution in Endgame, let us not forget what happens when smart Hulk loses out to rage. He turns to Banner with Savage Hulk's brain. So, he's weak and dumb.