This is what i meant that the user data is valuable otherwise you would have frozen out the existing users and have a web platform you would have to build up a userbase on again, which if this was the case then you would just start your own project as you are starting from scratch. The only upside is existing traffic to the website. Existing users who turn up one day to realise the content they have added is now gone would be a disaster for the user, then asking them to sign back up to recover that data is another unnecessary step.