Why couldn't Dr. Strange have dropped Thanos into an infinite fall like he did Loki in Thor: Ragnarok?

After rewatching Infinity War for like the hundredth time, it occurred to me that Dr. Strange was underused during the battle on Titan. Even Thanos mocks Strange for not using the time stone against him during their fight.

There is also that one scene earlier in the film where Iron Man, Strange, Wong, and Spider-Man duke it out with Black Dwarf and Ebony Maw.

Wong defeats Dwarf by teleporting him to Antarctica. Cull tries to jump back to New York through the portal, but Wong closes it just before his arm breached the portal, thus severing it at the forearm.

So, if these portals could potentially lop off the limb of a super-strong alien brute like Cull, then why couldn’t they have done the same to Thanos? When Mantis had his mind subdued, Strange could have done the same thing: dip Thanos’s hand in a portal leading to the sun, or some other place where the Gauntlet could not be retrieved, then close the portal, thus amputating Thanos’s hand, and taking the Guantlet with it?

Just another theory, but since Strange supposedly went ahead and reviewed all future outcomes of their fight with Thanos, I guess he didn’t bother with that approach. It seems pretty fool-proof to me, but then again I’m not a Sorcerer, nor do I have multiple PH.Ds, nor access to a magic rock that can allow you to bend time to your will.