That only unlocks the bootloader, which then allows you to install a custom one. There is no built-in option on Android for gaining elevated priviledges in any form, not even in a restricted way to disable bloatware that might compromise your privacy, and rooting your device breaks OTA updates, which also include security patches.

It does. Unlocking and gaining elevated privileges through rooting trips Google's SafetyNet API which will lock you out of many apps and/or features. It also breaks your device's Widevine certification so you can't watch DRM-protected video from many services.

As for the "We do not control our own devices, we cannot stop certain processes on them, and we do not know where our personal data is sent.", with stock Android provided by an OEM, you have no control over the opaque and invasive monolith that is Google Play Services and there's no way to control what data exits your device, aside from installing a VPN-based firewall. You can't even control when apps have access to your data, just a binary on/off switch.

Of course it breaks DRM. That's the point.

> with stock Android provided by an OEM, you have no control over the opaque and invasive monolith that is Google Play Services and there's no way to control what data exits your device, aside from installing a VPN-based firewall.

This is true of all systems (and even worse on iOS, which has the same data collection as Play Services but can't be disabled or avoided) and irrelevant to the discussion about whether a user can completely control their device if they wish.

That's a different question. You own the device. Now you are demanding that other services interact with your device regardless of how it is configured.