I helped one of my clients swap from their "bespoke" solution (dodgy bash scripts and an S3 bucket) to Snapshooter which made our lives a lot easier. Looking at Backupsheep's website it seems like it is very similar to Snapshooter, so I think that would be your best replacement.
IIRC, the initial development was in the mid 2000s but it was abandoned several years later because they couldn't get Unicode support working correctly. By the time it was abandoned there was already a lot of material referencing it like books and conference talks. So when the PHP team decided to do a new major version most of the planned PHP 6 features were already added to 5.3 and 5.4 so they thought it best to just skip 6 to avoid confusion.
That's 4chan. The other big site is 8chan, where users can create their own boards and there are less rules, which makes it much harder to moderate. Then you also have all of the smaller chans which tend to get spammed by bots posting illegal stuff like child porn.
Chans allow anonymous users to upload images and historically this leads into a lot of illegal content, especially stuff like child porn, to be uploaded unless you have strict moderation.