Exactly. The idea of always cropping to square makes little sense to me. The crop ratio is determined by the shape of the subject, and/or what else is useful to include in the shot for context. Since the longest edge will always be limited to 2048 pixels on upload, by insisting on a square crop you are then increasing the shortest edge from whatever it would have been otherwise, up to also being 2048 pixels. And all you are achieving with that is to include additional irrelevant background data which only unnecessarily increases the file size, and thus energy usage and storage costs. It may also make it more difficult for the machine learning algorithm to correctly pick out the subject.
Be wary of opinions. If you wish to understand the reality, then better to go do your own tests comparing different compressions and resolutions. It seems pretty clear to me that the current approach of significantly compromising on resolution while using only minimal compression (i.e. excessively high jpg quality) is sub-optimal in terms of the average resulting ratio of preserved detail to file size achieved. Though in fairness, iNaturalist still does a better job of this than most websites, and it is a bit tricky to come up with a singular approach that works well across the full range of image sizes and qualities that get submitted here. This topic has been discussed in more detail in the thread below:
https://forum.inaturalist.org/t/increase-max-image-size-from-2048-x-2048-pixels/13627/