Probably because it was a generic ideological comment, pointing further in the direction of generic ideological flamewar, which is tedious and repetitive and something we're trying to avoid here.
Socialist economies need growth or else all your citizens start leaving and you have to build a wall. That and it's cruel to not let their economy grow when everyone started out in poverty. China is obsessed with economic growth.
Hardly any economic motivations are removed by getting rid of shareholder capitalism; you still have markets, a growing population, and you still need productivity to increase.
Oh, and eliminating growth would destroy the environment because 1. environmentalism is a luxury good 2. low-productivity technologies consume much more resources than modern ones do.
I agree. However, the type of growth you're addressing here is different from the growth in social media companies. The growth in ad-tech based companies are by nature very artificial when put in economic terms. One can easily argue that these companies provide value by enhancing the reach and personalization of your marketing activities which results in increased sales and brand exposure. But at the very end of the day, how is an ever increasing of consumer spending GDP going to solve real life and death issues? Growth becomes relevant because capitalism is very focused on generating profit, you can either increase revenue or reduce cost, which one is easier? Increase revenue which then leads to, "let's get more users".
Edited: Downvoted without a comment, why?