Modern smartphones: "Powerful", "marvelous", but corporate overlords dictate what you actually get to do with it.

They lock your bootloader and prevent you from installing third-party operating systems.[1] Now they are starting to block third-party app installation only in certain situations, but this will sure as hell escalate.[2]

They block you from using the MicroSD card properly or take away the memory card slot entirely, decide what you are allowed to screenshot[3], and they lock your user data (like browsing history and saved pages) away from yourself to "protect you" from imagined evils. But this "protection" is actually the curse.

They also refuse to implement features people ask for like always starting with the rear camera regardless of the last used camera[4] and let the user backed up saved pages[5]. Something as simple as turning the flashlight on and off while recording a video took over a decade for Samsung to implement when shouldn't have taken a single afternoon.

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Sources:

[1] Xiaomi prevents unlocking the bootloader but graciously allows it seven days after purchase. I believe that as the buyer, you should be able to install any operating system you like.
[2] (added through edit, hence last) Since Android 16, Google blocks APK installations during phone calls, supposedly to protect against scammers. But if history teaches us anything, it means this will quickly escalate and end with APKs being blocked completely or only installable through ADB, which requires an external computer and a USB cable.
[3] Google and Apple let app developers block users from taking screenshots. This is, for example, used by WhatsApp to prevent screenshots of profile pictures, even though everyone knows one should not put something in a visible spot on the Internet that one does not wish to be preserved. I believe people should have the freedom to screenshot anything that appears on their screen, like desktop operating systems (Windows and Linux) do. The buyer deserves to have the final say on a device they paid for.
[4] https://r1.community.samsung.com/t5...
[5] https://forum.developer.samsung.com/...