The ESP8266 (the predecessor to the ESP32) was initially sold as a wifi IC, using an AT protocol over UART to communicate with the host MCU. Then some people di

The ESP8266 (the predecessor to the ESP32) was initially sold as a wifi IC, using an AT protocol over UART to communicate with the host MCU. Then some people discovered how to use it directly as an MCU, and the documentation and SDK slowly started being made available. As for why? Regulatory (FCC) compliance is probably a part of it, I think the ealy ESP chips were dubious in this regard. Licensing might be a factor as well (a lot of wifi chips use ARM cores; Espressif doesn't, though not sure how much of a factor this is). Support comes into it too - established wifi vendors provide support and help you with RF designs; Espressif has forums (maybe larger customers get proper support now?)