Earlier quoted context omitted.
They literally just posted this a few days ago https://twitter.com/WHOWPRO/status/1243171683067777024 when we know it's false and that masks do offer some level of personal protection on top of making everyone around you safer, given that you can infect others while asymptomatic.
Okay, yeah, the mask thing absolutely blows my mind. I have absolutely no idea what their motivation for saying this is, when just about every expert in every east Asian country disagrees.
There's also some evidence that widespread usage of masks may be effective in lowering the risk for such a disease, but deploying widespread usage of masks equitably on a global scale is nigh-impossible right now, so it's counterproductive to focus on it. Distancing is achievable instead, and leads to a similar result.