Pure Android was sparse in terms of features and what you got in the end depended entirely on the phone maker. Most would advertise with stupid features and see what stuck, like Samsung's S4 with it's gesture control and scroll by inclination (both fucking stupid).

Actually useful features weren't as marketable and didn't get attention they deserved until the big brands got serious competition by cheaper Chinese brands. Xiaomi had a massive cult following back in the day for having the best Android UI at the time.