There's loads of geographical names without this colonial backing in Europe. Scandinavia, Iberia etc. These names were not usurped and used to represent a singular colonial power. "British", however, was, and thus cannot be used neutrally to refer to Britain and Ireland.
God this map pisses me off to no end. Not only is it straight up wrong, the insistence on using The British Isles when it is a term inherently tied to British colonialism is just offensive
Over the centuries this language shifted and then you have the Acts of Union which formalised the name Great Britain. Then Great Britain became a colonial power, The British Empire and thus The British Isles became a colonial term. Islands ruled by Britain.
HELP?? Tohsaka Rin has SIX people after her in my Tomodachi Life game. She rejected three, but two asked her again and now she's dating Chrom Fire Emblem 😭😭😭