From Wiki:
When PKGBUILDs receive enough community interest and the support of a Package Maintainer, they are moved into the extra repository (maintained by the Package Maintainers) <…>
So, librewolf package has 150 votes and librewolf-bin has 429 votes. And it’s 6th most popular package in AUR (by “Popularity” metric). Why it still isn’t in official repos?
I understand why things like yay or google-chrome isn’t in official repos, but browsers like LibreWolf seems reasonable to include. Other browsers Brave, Zen, Ungoogled Chromium isn’t in official repos too, but Vivaldi is.
AUR package maintainers are not the same as Arch repo package maintainers. Anyone can be an AUR package maintainer.
And it is not straightforward to become arch maintainer. There has to be a level of trust in that person. The team shouldn’t be too big to manage. And there are other considerations too.