Why do we still shoot 23.976 if NTSC and PAL have been replaced? I watched this video and had loads of questions.

If NTSC ran into problems with colour and therefore slowed down 30 to 29.976, and 24 to 23.976, why didn't PAL have the same problems and slow down 25 by 0.1%?
If PAL and NTSC have been replaced DVB-T, ATSC, ISDB-T, DTMB, why do we still talk about them everywhere, and they show up in settings on cameras? So do the new standards display true 24 and 60 fps? What about 25 fps in PAL regions? Do PAL and NTSC regions still exist?
So, what is the point of my camera shooting 23.976? Why don’t we all shoot 24, and let NTSC TV slow down the playback at 0.1%? Alternatively, why not just shoot true 24 because all modern TVs can display it anyway? Is it something to do with the electronics in the camera?
The video says delivering at 24 is obviously for DCP projection at digital theatres. So does that mean that if I shoot and deliver at 23.976, it won’t project properly? Why don’t we all shoot and deliver true 24 if TVs can display it anyway? Why is there still this issue with 24, 25, 30 fps, depending on NTSC/PAL regions of 50/60Hz?
So what happens if I shoot 23.976 and deliver at 24? Will there be duplicated frames? Or does it become shorter in length? Vice versa, what if I shoot true 24 and deliver at 23.976? Are there skipped frames? Or does it become longer? Likewise, what about compatibility with 25 fps? Say, if 23.976 or 24 was to be broadcast in PAL regions, which you mention have been replaced?
23.976fps still exists because it's a standard. Cameras became designed to shoot it, non-linear editing software suites were designed to edit them, and devices were designed to play them. Even though NTSC went away, cameras still shot in 23.976fps. Even if they could shoot a flat 24fps, it causes issues in the edit room.
Putting 24fps footage on a 23.976fps timeline will have some issues but can be mitigated by being slightly slowed down or with pulldown. However, you will run into issues with multi-camera setups and syncing audio, hence this
discussion about editors complaining about audio sync drifting.
In the end, 23.976fps still a standard because if cameras switched to 24fps, it would cause issues in the edit room, and if editors used 24fps timelines, it would give pretty much everybody after them in the pipeline a hard time. Even if everybody could adapt to 24fps, most delivery standards are designed for 24fps anyways, so it'd have to be converted back to 23.976fps at some point in the pipeline, therefore it'd make it much less of a hassle to just shoot at 23.976fps anyways.