Part of the reason for that is that the iNaturalist taxonomy structure doesn’t have an option for “species group”, which is a categorization at a similar level but without the implied complications about separating species. So a lot of groups on iNat are called complexes when it would be more accurate to call them species groups.
All the taxonomic levels and how we decide where to categorize organisms into them can be pretty arbitrary, and as @aspidoscelis said earlier it’s done a bit differently between different taxa. However generally a complex covers just a handful of complicated and closely related species. A genus can cover a handful or hundreds or thousands of species depending on how closely related they are and which taxon it’s in; my impression is that plants tend to have larger genera than animals. The genus Taraxacum has hundreds of species, which can be subdivided into like 50 smaller groupings (a lot of Asian ones in addition to the European ones in discussion here) which are called sections. It happens to be that a bunch of the European sections do apomixis and so there’s a proliferation of microspecies in those sections. If it only affected a smaller number of species then it would make more sense to call them complexes. And again maybe when raspberries do apomixis, different taxonomists have decided on a different solution for categorizing them, I’m not sure.