[rixrax]

Why is this?

[joecool1029]

Takes time to bring up devices, LOS is a volunteer project, and manufacturers don’t send them devices like they used to. Finally, no matter what they rely on the manufacturers releasing kernel source for a release and some take months and ship squashed and/or incomplete source. Availability of bootloader unlocking is a factor but what I just said is the bigger reason for the delay.

[snvzz]

Because it is more profitable for smartphone makers if you need to buy a new one.

Unless there's legislation to force them to allow enrolling new keys or otherwise disabling secure boot, the abuse will continue.

[realusername]

Third party roms also do not include all the bloatware and spyware they are loading into the phone, they aren't a fan of losing control.

[EgregiousCube]

This is true; there is additionally a valid argument that there is security benefit to locking down the bootloader. I don’t like locked down bootloaders, but I get the argument.

[sspiff]

Most modern manufacturers disallow unlocking the bootloader and flashing unsigned firmware, which is a requirement for this kind of thing.

[c0l0]

LineageOS isn't unsigned, it just happens to be signed by keys that are not "trusted" (i.e., allowed - thanks for the correction!) by the phone's bootloaders.