No one said that ISIS and AQAP are the majority, the world’s Muslim majority doesn’t even live in the Arabian peninsula they are however 2 of the most powerful Sunni groups in the region with a very large support base in Saudi Arabia and one of them will take over if you get rid of the royal family.
It’s not about liking or not liking the person in charge it’s about being able to do something about it without causing even more mess.
The entire region is royally fucked with the exception of one country and it’s not just the US (NATO) and Russia (USSR), not to mention colonialism to blame.
Heck look at the election results in Lebanon this weekend, they are perfectly capable of fucking themselves over without any US intervention.
P.S.
If your measure of power is ones ability to attack the US at home then by that definition alone AQAP and ISIS are the most powerful entities in the region as no one else has any logistical capabilities to project their force outside of their geographical sphere of influence.
In a hypothetical scenario possibly the only one in the region that could do that currently is Israel if they modify their satellite launch vehicle into an ICBM and even It might not have the range to hit the continental United States with any payload.
The Iranians are probably half a decade away from a similar capability.
They might be able to use the stronghold they established trhgouh Hezbollah in South America but that wouldn’t be any different from the asymmetrical warfare AQAP and ISIS are capable of implementing just with an IRGC flare to it.
No one in the region has military bases within striking range of the US,no one has an aircraft carrier, no one has the logistical capabilities to wage even a ground war further than a few 100’s miles from their borders.