I don't believe and never suggested that wearing masks is 100% effective. If wearing masks was 100% effective the epidemic would not have spread in many areas where masks were required. But if 95% percent of the population don't wear masks and don't engage in social distancing, and are actively engaging with hundreds of people (versus a few family members), etc., the likelihood of spread of Covid (and some other viruses) is increased.
There is no guarantee that if you follow every precaution as perfectly as you can that you will not become infected. But if you are surrounded by people who don't follow precautions the likelihood of spread increases. The same thing might be said of other common infections on ships such as norovirus or flu during flu season.
As for masking, it is obvious that for various reasons mask wearers experience different levels of discomfort when wearing masks. For some it is not a big deal, for others it is much more troublesome.
What is important is that guests be aware of their own tolerance for the many Covid-related variables that can occur on a cruise. If Regent and other lines are not open about what is actually occurring onboard, then potential guests are deprived of crucial information that would go into making an informed individual decision about whether to cruise or not.
And when guests are onboard, then I think they have every right to know the status of any transmissible infection whether it is norovirus, Covid, flu or anything else.