Notifications drive engagement.
That’s the main reason why there are so many apps on the phone app stores.
Imho the biggest risk is your users go do something else with their time possibly by paying more attention to someone else’s notifications! 
(Btw interesting side note: the way I all but stopped using and ended reliance on WhatsApp and moved to Signal for 99.9% of personal messaging was simply by turning off notifications for WhatsApp. I didn’t even need to uninstall it)