[jfengel]

Does "adopting an emoji" mean something other than "appearing on that page"?

From the adoption page: Each adoption comes with a digital badge and certificate that you can proudly display.

[Implicated]

It also appears to be a $5k permanent backlink from unicode.org, custom anchor text even.

[nkrisc]

It’s a fun way to donate.

[thrdbndndn]

It's just a way to donate, similar to lots of "adopt a xxx" programs.