Professional embedded developer and Arduino afficionado here: the amount of misinformation and hot takes here is astounding. First, Arduino is aimed at making technology usable for non-engineers. The ease of use makea them a breeze for engineers though. There's nothing wrong with making something serious with Arduino as long as the project fits within the confines of Arduino.

Arduino refers to a company as well as a hardware and software platform. It doesn't only mean an ATMega based board. You can have an ESP32 based Arduino board.

Arduino boards aren't designed for high performance or very high speed signal integrity.They are designed to be easy to use by non technical people.

I see people saying stuff like the ESP IDF and FreeRTOS are easy enough to use for most people. First, Arduino on ESP32 is built on the FreeRTOS based IDF, so people who would rather use FreeRTOS don't exactly know what they are talking about. Second, anyone who thinks FreeRTOS is easy enough to use for Arduino's core audience is delulu.

Use the proper tool for the job. Arduino is for beginners, non-technical people, and for projects with undemanding requirements. Stop pretending that it's a half baked solution for engineers; that completely misses the point of Arduino.