I would only note that some objects practically cannot be photographed properly (allowing reliable identification of the species) in the wild. These are both microscopic objects and species whose identification requires special dissection of the specimen or special angles at high magnification (which is rarely possible in nature) - many insects.
As for cases, when a specimen was not collected personally by an iNat user. If there is sufficient data about the place and time of collection, and there is proper consent of the collector, and explicit attribution is given - it is not clear to me how this differs from posting a photo taken by a non-user (under the same conditions of good faith). The actual author (the collector) may not be willing or able to use iNaturalist, but may be willing to have someone else post their observations. Why should specimens collected by me (e.g. https://www.inaturalist.org/observations/65588120) be considered wild and those collected by my colleagues (not a iNaturalist users - e.g. https://www.inaturalist.org/observations/107864918) be considered captive? Is the biodiversity knowledge value of such observations lower? Is there something that distinguishes them that allows them to be considered casual?