What are two reasons advertisers should consider engagement when marketing apps?

Advertisers should consider engagement because a significant percentage of app users churn after three months. This high churn rate means that simply acquiring users isn't enough; sustained engagement is crucial to retain them and maximize the app's value. Additionally, some users download apps and then forget about them. This highlights the need for ongoing engagement strategies to re-activate dormant users and ensure the app remains top-of-mind. "Apps can be accidentally uninstalled" is a minor technical issue, not a primary driver for engagement strategies. "Users who haven't yet downloaded an app might need extra incentive" relates to acquisition, not post-download engagement.