Not all companies need or can even hide customer counts. In our business, one can easily guess our userbase by looking at how many maps are in our database. We could hide the total number, but a few simple searches would give a person an idea of what it is. As a result, we publish user counts and route counts. I don't think there are great benefits, aside from showing our users we are growing and have some substance, however, I also don't see there being much harm.

I can see a company that provides mockups or time management tools being able to hide this info (it's not intended to be publically consumed), but in our case it's difficult.

I guess creating a sense of complacency in the competition is a good thing. They might be more worried if they were watching huge growth in a competitor, but if the underdog is coming up with big growth anyway, there isn't much the market leader can do to prevent it...