Tweetanor, she's not just anybody, she has a great CV: product designer at Twitter, no less. She talked about design at several levels: for a billion people, for one hundred or for just one.
An important reminder for the world's designers - you are doing it for someone, a real person is on the other side of the screen, with their own experience and their own specific expertise. Because yes, although creative people are used for everything, like the Swiss army knives of communication, they all have a specific talent, something in which they are more talented. Something they love to do.
This is the case in your team, whatever its size. Charles is a fan of UX, Martine loves coding and someone else will enjoy being challenged by their clients. The bigger the team, the more these talents can be used for specific purposes, no doubt. However, it is important to make good use of these things for which everyone has a lure and a specific gift, whatever the size of the team: when we do something we love, we don't have to spend a single day working and it is important for each group member to feel useful and fulfilled.
That said, Eleanor quickly brought us back down to earth. People also design for languages (IT or not) and different cultures. What works in India will not necessarily work in Japan. There is a whole world between a multi-coloured hotchpotch and the purest minimalism. We will all be more effective if we are designing for our own culture (iOS or Android, they are also "cultures").
Is the Twitter interface adapted to all these specific features? It is very simple, after all. But as Eleanor reminded us, design does not mean not making something beautiful, but something effective! If we consider that we tweet without even having to think about it, it probably means the aim has been achieved. Temporarily at least... because a design is never finished. It develops like behaviours (whose developments can potentially be predicted) and is never "perfect". A work that is constantly put back on the drawing board...