We periodically get the "Help me size my wholly unspecified application" questions, like What capacities should have a hosting to support an average of 1000 registered users simultaneously?What capacities should have a hosting to support an average of 1000 registered users simultaneously? or Server requirement for running an application having huge network trafficServer requirement for running an application having huge network traffic.
Have we already worked up a canonical answer for these types of questions?
To a comment I made on the first question cited abovethe first question cited above, @squillman said 'Yeah, the canonical duplicate is "Not a real question"', but I'd argue that there's probably some value in a well thought out answer describing the need for a scientific process of capacity planning.
To my mind, anyone who would even think to ask such a question is clearly in need of some basic guidance (and, hopefully, can be made to understand that there is science to capacity planning and that "number of users" or some other catch-all value isn't the only data point used in planning). Closing these questions as "not a real question" doesn't point the OP in the right direction, and they end up still living in their happy fantasy world of cut-and-dried capacity planning via a single data point.