Many Kodi addons are developed to scrape the internet to find streaming video links. A lot of the content found online is not properly licensed for distribution, so the addons end up providing pirated movies, live sports events, and TV shows.
Due to the unrestricted nature of many addons’ search capabilities, copyright watchdog groups such as the MPAA often threaten third-party Kodi addon developers with litigation. This is one reason most long-time Kodi users only access streams through an encrypted VPN.
The legal threats and harassment are also usually enough to make many developers give up on their projects. Aside from this, some developers end up abandoning their addons for personal reasons such as working to pay bills, going to school, or loss of interest.