Hey, you're totally right. Actually we would normally use some embedded solution for that (preferably STM32 or ESP8266 if wireless was needed), however, in this case we were focusing on designing it in a way so that it's easy to maintain by web-development agency, which we are. Not everyone here knows how to change and flash low-level code into a uC but almost everyone would be able to fix a bug in python code on the RPi :)