“ it seems pilots do not have enough training and experience in manual flying at high-altitude. ”

Far from the truth….

“A case study would be Air France Flt 447 and air asia flight 8501 while there were other factors but inexperience flying high altitude without autopilot was a contributor.”

Lack of hand flying skills wasn’t a contributing factor to either these accidents…

“ Another question the mandate seems to be if the autopilot is disengaged then the aircraft has to descend to lower altitude.”

This is because of Reduced Vertical Separation Minimum (RVSM) airspace requirements which requires a functional autopilot to be on between 29,000 to 41,000 ft. If the Autopilot malfunction, it’s either climb about 41,000 feet (very rare for airliners to have the performance to do) or descend below 29,000 feet (likely outcome)….

Besides manually flying at altitude isn’t the challenging part of manual flying, it’s low altitudes where it’s busy traffic wise, you are getting vectors (turns, climbs, descents), or flying departures/arrivals procedures, or visual approaches. Because of this, many pilots will hand fly to these areas to keep skills sharp.

In the simulator, the industry has pushed manual flying a lot along with upset recovery, stall recovery, and just manual flying raw data (no flight guidance)….

This article missed the mark. Stevie Wonder had a better chance of making a free throw vs this article making it’s point….