Important point here: You are not representative. If you are on Hacker News, you have probably been called brilliant at least once. You are almost certainly, given that you don't seem to be a non technical co-founder in a startup, in the top 5% of the population for mathematical/logical(not necessarily arithmetic) abilities. Just because you find the calculations tedious does not mean that most people don't benefit from them. From what I recall, most people forget a concept that they are exposed to once and only once.