The Belgian government said the same, but I think the message isn't quite as black & white, and should be seen through two pairs of eyes:
1. There's the individual, in which case wearing a mask is not super useful. Wearing a mask isn't very effective at preventing the wearer from getting sick, especially if the wearer is a typical human being who is constantly picking at their face and generally doesn't wear the mask properly. This was oft repeated near the start of the pandemic, mostly by doctors and virologists who deal with infection on the individual level.
2. There's the collective, where reducing the spread even a little bit, can have a definite impact on many people in the long run. Masks mandates are definitely useful there, at least in crowded places. Even if they're not being worn properly by a large fraction of the population, spread will still slow. This may not be useful for any given individual, but it can help "flatten the curve" of hospitalizations, which is sort of what the management of the pandemic is all about. This wasn't really elaborated on in the media, but it's the message that biostatisticians and epidemiologists have been bringing all along.
I think there's been some serious communication issues throughout this whole pandemic. Not just in our respective countries, but pretty much globally. Covering your nose and mouth is super low effort and super low risk for almost everyone. And while staying at home and away from people is even more effective, going about your business with a mask is much easier for many people. I don't know why more effort hasn't gone into trying to convince people of that. Instead we're chasing pipe dreams of cheap respirators and tracking apps. Techno-fetishism at its worst.