Nicotine-free vapes still develop the oral habit in children and has been shown to be an easy entry into other vapes. Also propalene glycol really isn’t great for your lungs, and constantly sucking on a vape that uses it does negatively effect your breathing.
https://www.news-medical.net/news/20191018/Vaping-propylene-glycol-and-vegetable-glycerine-may-lead-to-lung-inflammation.aspx