Batteries are easily replacable. LCD can last a long time, my main desktop monitor is 18 years old at this point. OLED less so, admittedly.
Not in most phones. You always have to mess with glue and unless you take extreme care and caution to remove _all_ pieces of it you will end up with compromised water-tightness, not to mention risking the screen cracking or being exposed to air (ruining OLEDs).
> my main desktop monitor
We were talking about phones. Phones get dropped, scratched by keys, ... the list why phone LCDs/OLEDs can get broken is loooong.