As an educator, I’d also note that many of the people uploading to this site are newly engaging with nature. They have quite a learning curve ahead of them. For example, I’ve had discussions with people who were utterly shocked to learn that there is more than one species of “seagull”. I’ve also seen a few times where someone who started out uploading what some would consider “bad” images quickly improved their observation skills and became incredibly knowledgable, prolific uploaders. We’re all at different stages in our engagement with the natural world, and I actually kind of like how this site reflects that (despite occasionally being annoyed while trying to ID others’ observations).
As for the actual ID part… yeah some assumptions may be being made in certain cases. I can’t and won’t try to defend every identification made. From the uploader’s perspective though, without some prior knowledge it’s hard to know which blurry photos might be identifiable (e.g., I’ve seen some pretty terrible photos of pelicans which were nonetheless clearly identifiable) or not (e.g., a generic sparrow with no discernable markings). Only way to find out might be to upload and see what happens.