A very good reason. I refuse to use paper straws. They are disgusting (it feels like sucking on a piece of printer paper).
Don't get me wrong. I try to remove plastics in all areas of my life as well (because of microplastics), but can't they coat the surface in some biodegradable polymer like PHA/PBS?
Or if this is too expensive coat it with some beeswax at the very least...
Try bamboo straws, they work very well and are as green as it gets.