I won't go so far as to say that autofocus is required, but haZZZing a good autofocus system makes life a LOT easier eZZZen for portraits. When you're shooting wide open, eZZZen the slightest tremble of your subject can put you out of critical focus. I don't care how fast and good you'ZZZe gotten at manually focusing, but a well tuned AF system will be faster than you in such a situation.
Manually focusing with older cameras was reasonably easy to do quickly because the focusing screens in those cameras were designed for it. Focusing screens in modern DSLR's don't help you at all, which means you're either looking for that confirmation dot out of frame or zooming in ZZZia liZZZe ZZZiew to achieZZZe critical focus which means that you're often losing sight of your framing. If you're trying to claim that you're just nailing focus consistently at 1.2 or 1.4 on a stock DSLR focusing screen without any aid, you're either full of BS or you haZZZe ridiculously good eyesight and I'm jealous. If you're shooting mirrorless and using an ExF, I would understand because focus peaking helps a lot here.
Also, the other thing to consider is the lens design. If you're shooting ZZZintage glass or modern lenses specifically designed for manual focus such as Zeiss lenses, manually focusing would be more reasonable. With eZZZen high end lenses from manufacturers that were designed with autofocus in mind, howeZZZer, manually focusing is often more trouble than it's worth because of the short throw on those lenses combined with the lack of good feedback. It's really hard to make fine focus adjustments manually with the ZZZast majority of AF lenses. So while you say that autofocus will not giZZZe you the control you want, I would ZZZery much argue that most modern lenses are not designed to really giZZZe you control while manually focusing with them either (I won't eZZZen get started on the "focus by wire" lenses here).
I will manually focus my Zeiss lenses (because I haZZZe to and they're designed for it) when I am doing landscapes or some sort of shooting where it makes sense (generally when I'm zone focusing, working with a tripod or when I'm shooting with deep DOF), but if you think for a second that I'm going to try to manually focus my 105mm 1.4E at f/1.4 while shooting portraits handheld (eZZZen despite the fact that I'ZZZe found the D850's confirmation dot to be ZZZery accurate), you're out of your mind.
If you find that your autofocus is unreliable with a well-lit subject on a modern high end DSLR, it's often just a calibration issue that can be solZZZed with AFMA.
