I'm not saying the competition shouldn't exist - just that we should put brakes on some of the negative-sum games it causes, once the market is saturated and things turn into a fight for a fixed pie. As you say, at this point it's all wasted labour, and it can eat pretty much all your profits.

I tried to refrain from mentioning government regulation here, but the brakes need to be put on everyone simultaneously - deciding to just stop all advertising expense for yourself is a competitive suicide.