“So, why should we celebrate Greta Thunberg being named Time Magazine’s person of the year?”
Because she’s young (thus having a greater claim to “the future”), committed, absolutely correct about climate change, witheringly clear, endearingly free of emotionalism and self-promotion, and more effective at public advocacy and consciousness-raising about the need for profound and immediate socio-economic transformation than anyone else on the planet. How she did this is immaterial but the fact is it’s done and she’s using it to maximum advantage for her (and our?) cause. She’s on the cover of Time Magazine for the same reason Obama wanted to shake her hand, TV hosts want her on their shows, and UN conferences invite her to speak: because they all want to attach themselves to her authenticity to make up for the deficiencies of their own. Many people high, low, right, left and center are envious of her, and that envy merely illuminates the extent of their bullshit.