You are correct on all points there (especially the last point), but why does a purely digital HD signal, still need to be designated as PAL or NTSC?
well, it doesn't need to be designated, as said this is used for historical reasons.
analog and digital formats don't have that much in common. digital sd formats have numbers of scanlines and fps so that analog fits in nicely, but hd digital formats...no, there are no real simillarities, be it luma or chroma encoding.
kedasprobe
Is it just nostalgia or habit that we don't let go of these two acronyms?
it's easier for the customer to differentiate what he needs as a format for his living room if you give him "pal" and "ntsc".
ie
it was in the days you only had dvds and crt tvs that may or may not support pal60,etc.
today it's kinda moot as most new tvs support anything digital.
if you have the right codec and container. 
electr_peter
Personally, I am happy if video is at least BW and is focused. Digital/analog is just a technology difference which does not guarantee best quality by itself. On the contrary, digital video allows broadcasters to be cheap and transmit extra crappy compressed video signal.
i always saw BW as an abomination and totally inhuman experience.
crappy compression part, i agree. just look at the many yt videos and sometimes even broadcasts of that overcompressed modern codec crap.
essentially good analog pal transmission beats mpeg2)and newer codecs), but the fact is that it was never that easy to get perfect analog reception.
teh fact is also that most people wouldn't be able to see that difference. and one more fact: hd beats analog pal's sd.

(offcourse, unless you upload that hd to yt..then all bets are off)