Motorola promised Oreo for the Moto G4 Plus when it launched in 2016 and went back on its word a year after. Media outcry over that betrayal forced the company's hands, making them promise Oreo as initially agreed. It's been eighteen months since then, though, and the Moto G4 phones are only just starting to receive the Android Oreo OTA.
https://www.notebookcheck.net/Eighteen-months-after-the-merry-go-round-the-Moto-G4-and-G4-Plus-are-now-receiving-the-Oreo-update.411860.0.html