I think of optimization as trying to get the best score with the current systems and setups you've got, meanwhile the "parse brainrot" or whatever folks choose to call it blames lost dps on others, be it party members or the game itself.

The former's more of a personal challenge (fun!) while the latter tends to call for changes made to the game to reduce their dps loss, often removing optimization steps (not fun!). We've gotten to the point where we're debating even the most minute deviations from the optimal striking dummy rotation.