But I agree that the initial friction to setup LineageOS on the device is far too high for a non-technical customer, Something which could be only resolved if a devices ships with LineageOS(I think even F(x)tec, Fairphone requires the user to flash LineageOS) but then again memories of that fateful tie-up with device manufacturer which ended CyanogenMod would be fresh within LineageOS team.
Now that's the catch-22, Alternate exists but not for everyone.