You're being little too quick to judge here. This project represents software running on an embedded device to collect, process, store and display measurement data in realtime from the real world. Like something you could connect to a solar panel or a small battery pack and put outside in your greenhouse.
Nerves is an incredibly powerful tool. It will burn a firmware image to an SD card for you that you can just insert into your device and boot. It's almost like magic. There is also an elegant OTA (over-the-air) update process so that you can update your device remotely, where it deals with managing disk partitions so that the system can pull the new image and boot into it without the need to remove the SD card. You also get the benefits of lots of community work for supporting a big number of devices. And when what the community has created isn't working for you, it's all just open-source buildroot goodness so you can do your own thing. In a project I was working on I needed an external wifi adapter vs. the onboard one and was able to recompile a custom kernel to enable the right drivers. It was a lot easier than I ever imagined.
You also get Elixir - which is pretty rad in and of itself to have such a powerful runtime on a tiny little device.
So sure, you can do as you describe but you are only considering about 1% of this project: rendering data for the user to see. You are missing out on the fact that in order to gather that data you need to be able to communicate with some kind of embedded chip that is actually collecting those measurements, often via a very low-level communication protocol like i2c or spi. You need to parse the measurements, which are often not in a human-friendy format, then you need to get the data out/off the device so you need a network stack, your network might go down so you need a system to capture data and replay it once the network is restored, etc. It's really sophisticated! Seeing a book like this is incredible.
Nerves is an incredibly powerful tool. It will burn a firmware image to an SD card for you that you can just insert into your device and boot. It's almost like magic. There is also an elegant OTA (over-the-air) update process so that you can update your device remotely, where it deals with managing disk partitions so that the system can pull the new image and boot into it without the need to remove the SD card. You also get the benefits of lots of community work for supporting a big number of devices. And when what the community has created isn't working for you, it's all just open-source buildroot goodness so you can do your own thing. In a project I was working on I needed an external wifi adapter vs. the onboard one and was able to recompile a custom kernel to enable the right drivers. It was a lot easier than I ever imagined.
You also get Elixir - which is pretty rad in and of itself to have such a powerful runtime on a tiny little device.
So sure, you can do as you describe but you are only considering about 1% of this project: rendering data for the user to see. You are missing out on the fact that in order to gather that data you need to be able to communicate with some kind of embedded chip that is actually collecting those measurements, often via a very low-level communication protocol like i2c or spi. You need to parse the measurements, which are often not in a human-friendy format, then you need to get the data out/off the device so you need a network stack, your network might go down so you need a system to capture data and replay it once the network is restored, etc. It's really sophisticated! Seeing a book like this is incredible.