It may be an issue that families indeed do not want to disclose such thing. Where it is really detrimental is when families do not use medical help from fear of disclosure. At the same time, I am not sure whether it is a necessity to bring everyone together, and seems that various organizations feel the same way. If you have some friends, families, teachers around you who understand and support you – do you necessarily need to be with other people suffering from same things? As Avira testifies, there are lots of people who would be willing to help. Maybe, some are not sensitive because they are ignorant. I have no clue, for example, of the issues involved and maybe my suggestion above is not shaiach.
PS There are cases where people seem to benefit from talking to people in similar conditions. R Twersky Z’L for example highly recommended AA meeting to addicts (even despite christian roots), but this seems to be especially important when a person needs encouragement to change their behaviors. I did not hear, for example, that, say, people with casts on their hands would need others like that around them.