You are correct in your calculations, a RS has nothing to do with market cap. Your and my net value would not change. However many shareholders view this as the kiss of death and will sell, thus driving the price down.
A RS usually happens on this level so a company can continue selling shares at a higher price for whatever reason, and the price will continue dropping again. But this is not always the case as a RS ma mean bringing the share price up to qualify for a higher exchange. How each investor deals with a potential RS depends on their risk tolerance level and knowing what they own. I look at it as another potential opportunity.
GLTY
LLH