The main reasons you wanted a manual back in the day was price - because automatic transmissions were expensive - and fuel economy - because they were less efficient. (To a lesser extent reliability, because automatics were newer and they hadn’t worked out the kinks yet.)
However, the price of automatics fell, and the dual-clutch gearboxes with 7-10 gears are even more efficient because they keep the car in the most efficient rev range. Same goes for CVTs. And the dual-clutches shift faster than you ever could, so they’re better for sports cars, which is why F1 switched to them a long time ago.
So it makes sense that manuals are falling out of favor because they’re objectively worse in all respects compared to the transmissions available today. However, subjectively they’re a lot more fun which is why I have a manual transmission car I plan on keeping on the road well into the 2050s.