Is it important to have an SPF in your daily skin care routine? Yes.
So why would you not have an SPF in your lip balm?
The skin on the lips is very sensitive and thin and lip balm is normally wax based and oily. So essentially what’s happening is lip balm without SPF is being applied to protect the lips from chapping and then we’re going out on a hot, windy or cold day (all weather conditions can damage skin). You may aswel slather coconut oil all over yourself and go and sit outside and bake. It's not only sun damage, its also UVA and UVB rays that lips need to be protected against even when its cloudy as these rays can still penetrate through clouds and cause damage.
The lips need just as much protection if not more than the face and body as we’re eating and drinking etc throughout the day so any protection is constantly getting wiped away. Occasionally it may be fine to go without but overtime wearing a lip balm without SPF is encouraging premature ageing and skin damage resulting in lip wrinkles developing which could have been prevented or delayed.
I rest my sanitised case...