If you want to frame this as an ideological debate over freedom of user choice, instead of a very specific debate about a very specific App Store rule (even though the latter, and not the former, is what the email in the OP is about), then sure: you have the choice to select a device with a tightly-controlled ecosystem. You also have the choice not to. It was your choice to obtain this device, knowing full well that it would be tightly controlled. Or if you didn't know, you also have the right to return the device and no longer use it.
Get an Android phone and use the Play Store (or any of the 3rd party Android stores). The magic of a smartphone isn't only on iPhone and there's nothing you can do on iPhone that you can't do elsewhere.
Apple and Google have an effective duopoly on the mobile and tablet app distribution markets.
[1]: https://hindenburg.com/products/hindenburg-field-recorder