This isn’t generally true for eukaryotes either. In plants, hybridization is a huge thing and also polyploidy. So for some groups of plants we struggle to put them in neat boxes as well.

And zooming out to a larger view on taxonomy, plant taxonomy has seen some huge changes in the last decades with the various APG (angiosperm phylogeny group) publishings rearranging many if not most orders, families and genera of angiosperm plants.