2012 Olympics host team was Great Britain?

Why not United Kingdom?

https://youtu.be/4As0e4de-rI?t=11047

“United Kingdom” is not a place name, but rather a descriptor. Great Britain, because it is the "United Kingdom of Great Britain (and …) " So that tells people where the athletes (mostly) are from. Should be noted that various overseas territories and Crown dependencies also contribute to that team.

Just because, I think. When the modern Olympics was established, there was less pernickety distinction between geographical Great Britain and the United Kingdom (with or without the self-governing island dependencies). In particular, all of Ireland was still part of it.

And GB stayed the most convenient portmanteau term, both for the Olympic association and, I’d imagine, the most familiar internationally

In fact, the two-letter code for the country, uh, nation, uh, political entity is GB. This also has the added advantage of being a pair of initials which happens to stay true through translations to most European languages.

For the same reason that the Republic of Ireland and Northern Ireland are both on the “Ireland” team.

No, folks in Northern Ireland get to choose - they can represent the republic or the uk.

Technically, the name of the team is “Great Britain and Northern Ireland Olympic Team”, but the common logo is “Team GB”. That has been criticized for excluding any mention of Northern Ireland, as per the wiki article:

Puerto Rico has an olympic team and they are part of the US . I assume their residents can choose which team to compete for.

You probably mixed that up with Rugby (both, Union and League). Here, the national team represenents the whole Island of Ireland. They do not, however, compete against a British national team but rather against the national teams of England, Scotland or Wales (and of other countries). I am unsure how that would have been handled if Ireland would have qualified for the Olympic Rugby Sevens tournament (where Fiji took the gold medal, the country’s first ever medal)