

Because these glasses are quite powerhungry. If i remember correctly from a review a steamdeck used 5W more with the glasses plugged in and the built in steamdeck screen off compared to the steam running regularly. IDK how much the oled screen of the steamdeck consumes but the glasses consume those 5W on top of that!
A built-in battery for an adequate runtime would make those glasses even heavier, bulkier and goofier then they already are.
Back then i still clinged to the few active forums which were still around. I slowly started to switch to reddit 2016 i think.