I wouldn't call social media relaxing. After all, it's known as doomscrolling. I think reading is actually more relaxing. Social media is addictive, like a drug. Nobody calls cocaine relaxing.
What exactly does "mentally passive" mean? I doubt cocaine is that either.
Anyway, I don't buy the "energy" story, that doomscrolling is somehow low-energy, or even that people can't muster the energy for any activity other than doomscrolling.
Obviously I meant mentally passive, not physically passive.