People would 100% be jailbreaking this stuff.
Almost no one will do it - it's a lot of work, loss of warranty, loss of small conveniences.
In the U.S., this is not true. If Apple claims so, they are violating the Magnuson-Moss Warranty Act.
> a warrantor cannot, as a matter of law, avoid liability under a written warranty where a defect is unrelated to the use by a consumer of “unauthorized” articles or service.
https://www.govinfo.gov/content/pkg/CFR-2018-title16-vol1/xm...
your resale value is now zero
your service options have been limited to third party workshops only
In the U.S., this is not true. If the manufacturer claims so, they are violating the Magnuson-Moss Warranty Act.