iNaturalist has always accepted field sketches if they have diagnostic features. Yes, it’s hard to verify that the sketch was made in the field or that diagnostic features are drawn properly, but this also comes up with photos and other sorts of evidence. And as others have mentioned there is a very long history of using drawings to document biodiversity. The volume of sketches on iNat is quite low, and I don’t think there’s a significant data quality issue even in the worst case scenario here. Of course, if something seems wrong (out of range or habitat, sketch looks wrong or not detailed enough, etc) feel free to bring it up in the post.
people vary in artistic talent, of course, but people vary in photography talent or ability to distinguish species too. To me this connects a little with the ‘photo policing’ issues where people would pester users about blurry or unaesthetic photos. I would say just enjoy the sketches and if there are issues, use comments, disagreeing IDs, or data quality analysis as needed.
You can see a bunch of sketches here https://www.inaturalist.org/projects/nature-drawing-and-journaling and i encourage others to add to this project so for better or for worse they are easy to find.