And yours is a vast exaggeration. You do realize all of these phones are using either Qualcomm or Mediatek chips and designs which already have those tracking firmwares right?

All of these companies are using these firmwares. As for the Custom ROMs it depends on the device and the custom ROM you're using. So, calling them entirely working on reverse engineered is a bit much. That's why these so called free phones need hardware kill switches. Even that article you linked states this. So, unless these guys come up with 100% pure homemade hardware and Linux based OS they will never be free from tracking. Even then they won't be free from tracking. Hence my point: You can get the same level of de-google and untraceable stuff with using a proper Custom ROM suitable for your device.