People editing hosts files for other reasons was normal (a long time ago-- and it stopped being normal for valid reasons, as tech evolved and the shortcomings of that system were solved). A program automatically editing the hosts file and its website using that to detect information about the website visitor is not the same thing; that usage is novel and was never "normal."
This claim strikes me as obviously wrong.
There are also other reasons to do it, like if you want a device on the local network to be accessible via HTTPS. Getting the certificate these days is pretty easy (have the device generate a random hostname for itself and get a real certificate by having the developer's servers do a DNS challenge for that hostname under one of the developer's public domain names), but now you need the local client device to resolve the name to the LAN IP address even if the local DNS refuses to resolve to those addresses or you don't want the LAN IP leaked into the public DNS.
Or the app being installed is some kind of VPN that only provides access to a fixed set of devices and then you want some names to resolve to those VPN addresses, which the app can update if you change the VPN configuration.