This reminds of how when the unicode consortium had to add flag emojis, instead of opening the can of worms on what countries are independent or not, they just noped out of it and let the implementers decide which combinations of regional indicator letters render as country flags.
From Wikipedia:
I don’t think you’ll be able to find a source that specifically says “yeah, they did this to avoid having to make a decision about which countries are important/independent enough to have flags”, but like… why else would they go with this more complicated system over just defining separate codepoints for each flag?