The Multiverse understands his importance in each universe and thus made him that way. Strange may just be an ordinary guy with magical knowledge but he has always been a key factor that has protected our universe from the many threats against it. Strange fights Dormanmu on nearly equal footing while I have seen Yao here nearly die to a mindless one.
Mindless ones are Dormamnu's soldiers or minions, which ever you want to call them but they are far below Dormanmu in power yet the almighty Ancient One was nearly killed while fighting them but then again in his defence, the mindless ones are immune to a variety of things and love to swarm their opponents. As Yao put it in both the MCU and here put it, "Strange is the best of us all", that statement wasn't a lie because Strange indeed was the most powerful sorcerer but my existence has introduced medicine that were way more effective than normal. Technological treatments that can let you regain your lost limbs or broken limbs in days and some weeks to get used to.
(A/N: The Mindless ones aren't Dormamnu's minions in the comics but he does control them at times to wreck havoc on the Earth. Fun Fact: Dormamnu doesn't like them and also one of them was given sentience by Sir Isaac Newton and yes, he exists in Marvel and he is also a powerful sorcerer)
Now when Strange gets into his accident, he would just come here for treatment and we will send him back home in a month with fully restored hands so he wouldn't seek out Kamar-Taj and of he doesn't do that then Dr Strange the Sorcerer Supreme ceases to exist and boom!! More responsibilities on my head.
"Yes"
"Ahh… like can't you consider another Sorcerer supreme candidate like Victor Von Doom or Tony Stark, you and I know just how cool, Iron Supreme was"
"James, stop, I am serious, though I have to admit, Iron Supreme is cool and gets things done but this universe isn't like that, Anthony Stark may be a good fit for a Sorcerer Supreme but he doesn't have the potential, Strange has and neither does Doom. This Universe needs Strange" Yao said in a firm tone
"I understand you, Paris, where's Strange?" I asked
[New York City, performing a surgery on a kid, he's fine for now]
"Good, don't worry Yao, when he does get into his accident, I will direct him towards you though making him join the Mystic side of things is up to you, his mentor"
"Thank you, now I must be on my way, the integrity of this thing is becoming unstable" Yao said as he stood up and slowly walked back into the fracture in space
"Your welcome then, now good bye" I said and immediately closed the space breach.
That was new, I knew you couldn't open portal of any kind, magical or through science or some other means but leave it to Yao to figure out a way around it. The field could block portals from connecting to Elysium but it wouldn't even register an interdimensional breach like the one that occurs whenever someone enters the Mirror dimension or exits it but that also means that someone like America Chavez would be able to easily get into Elysium whenever she wants.
Even with this flaw noted, I don't think there is a real way of preventing it with science though Magic yes but with science, it was basically impossible. Yao is just a man that even in his old age is there to just tell people that he was once feared across the universe. Yao or more popularly known, the Ancient One is meant to be Strange and Mordo's teacher, the man may being his old age now and thus can't usemost of his spells but it is worth it to note that Magic is all about knowledge and this guy knows a lot.
Alternate Realities, speaking to other versions of himself, forbidden tomes, ancient knowledge lost to the world etc. His feats in the comics were nothing compared what I have seen this guy achieve in his youth… or at least what Paris has shown me he could do in his youth. There is a reason why Dormanmu didn't attack the Earth throughout his lifetime…. Well he did but he was sent packing but now he can't even beat a mindless one.
"Paris just keep an eye on Strange, Peter Parker and Wanda Maximoff. Those three are the main characters of this universe" I said and immediately I could already feel a headache forming
Strange while an awesome character was a huge pain in the ass, Peter Parker is okay and nice but then I would need to Tony Stark his ass like the MCU Tony had done and finally the walking disaster, Wanda, I don't even know where to begin with her but yet, I have to make sure they are on the right path. Strange was the protector of Earth, Peter is tied to the Web of life so his existence is incredibly important, Wanda is the Nexus of our reality… they are all incredibly important if this Universe is to remain safe without too much intervention from me.