There's evidence there might some benefit.
There's also evidence it will be of no benefit and make it worse.
Yesterday, on 2 news programmes several medical people pointed out that xiuntries like china, who have worn masks for years didn't ever see a drop in respiratory illness when they started wearing them. Viruses, flu are still spread on those countries at the same rate. There's no reason to think that same wouldn't happen with covid.
And yes, people using them wrong (not washing reusable ones, not taking them off properly, ignore social distancing, facing with them, practising poor hygiene) means that they could, potentially, make the problem worse.
Some people on another thread believes people could simply be trained to use the correctly. Yes they could. But people use safety equipment wrong all the time. On our local news, last night, there was a carer being interviewed with a mask, pulled down to her chin, on to her neck. Which is a big no no.
Even people who are trained will forget sometimes. Its known fact that some people react to being given safety equipment, by being more complacent.
I always wonder, as well, why people only talk about wearing masks outside the house. Masks provide some protection, from you, if you are symptomatic. How many people, who are convinced they will solve everything, wear them in their home?
If you believe wearing a mask will protect those people around you, incase you have it but but no symptoms.....why wouldn't you wear one 24/7 (changing regularly) inside the house when around your family.