The whole point of Killmonger wasn't to take on the Avengers or destroy reality like what Dr. Strange cares about... it was to evoke domestic terrorism in every country by basically doing what white folks do to 3rd world countries and projects by sneak supplying weapons to desperate factions, then sitting back while the countries destroy themselves until it's time to play 'savior'.
So basically a number of the world's presidents/kings would be dead, the countries in political chaos and disarray, military coups, and then Wakanda comes out of the shadows to impose their will.
The biggest issue is thinking all factions in every country would agree to pledge allegiance to Killmonger once that time came, instead of being power hungry/wanting autonomy [after taking control of their own countries resources]. But at that point pandora's box is opened by creating a systematic/multifaceted international mess, even if he was stopped as the supplier [or eventually stopped supplying].
It was a flawed plan as far as his end goal but it was a great fukkery filled plan as far as lasting effects everywhere that Thor couldn't just punch away, no more so than he punches away the boko haram or north korea, w/o causing further fukkery.
Would've caused even more fukkery and dissaray with Thanos snapping his fingers and all the Avengers reeling.