So as a techie I agree with you but as a user I don’t really think it matters. If your device exists to connect to public endpoints and uses mDNS for local discovery then any public DNS server should be fine. All these devices want is a clean connection to the public internet and you’ll never see them officially supporting blocking. At best DNS filtering is a hack that currently works because most people don’t do it and there’s little pressure to work around it. The device is free to exfiltrate all your private data through the connection to the manufacturer’s servers. It doesn’t really need DNS to do it.
I bought the device to stream content not to display ads. So you'd be happy if every laptop manufacturer installed crypto-miners on a new laptop you purchased without telling you before purchasing the device with no way to remove it.
It's no different than ads, they are using your resources without your explicit permission after the sale of the device to generate income for their company.
It's madness to me that people find this acceptable. These companies are profiting off the ignorance of people and misleading customers on what they're actually selling them.