I was wondering though, if you get into the muddy waters of considering 'indirect' sales and marketing costs (engineering, support etc.) and fixed costs (salaries), isn't the logical place to end up that you should just count ALL of your costs each month, and divide it by the number of new customers acquired?
Ultimately, ALL business resources must (or could be argued to) contribute to acquiring new customers in some way (if they don't, what do they do?!). This approach may actually be a useful dose of reality for many in the startup world
So, I can see the benefit of measuring CAC without these indirect costs, in terms of measuring the success / impact of specific marketing and sales activities, and I can see a very simplistic benefit of just counting all costs.
Struggling to see the benefits of the messy hybrid?