I think Apple are playing a very clever game not releasing sales numbers. Apple are always the bar other companies compare themselves against, you only have to look at tech headlines such as 'iPhone killer' or 'Macbook Air killer' to see this. Sales of iPhones, iPads etc are always compared by other companies.
Apple could be selling a lot more Apple Watches than we think , but other companies don't know if they are doing good or bad this time because they cannot compare them selves to Apple without this missing statistic. For example if Samsung sold 1 million gear watches how will they know if they are doing well? If Apple sold 30 million Apple Watches they would know the market is there but they are doing bad, must do better. If Apple sold 2 million Apple Watches Samsung would know the market for this is not currently that great. But Samsung don't know how well Apple is doing