When you say "Firstly, the stark popularity of those services would seem to suggest that for most people, they have done the cost/benefits analysis, and figured out it doesn't make sense. The effort involve simply doesn't make sense for them." do you understand that for many people, decisions are not carefully considered after collecting and reviewing all the pros and cons before arriving at a scientifically rigorous conclusion? It is far more likely that users just choose what their friends or work colleagues use, based on word of mouth recommendations. The 'network effect' is what this is called.

There isn't much 'miscalculation' happening in these scenarios, there may be little to no calculation at all.