Babel wrote:
If the website is getting revamped anyway, I honestly don't think it's a bad idea.
You could argue that a rebranding of the website, and probably some more marketing, would make new people interested in using the site, so deleting users who were last seen 5+ years ago would be optimal to free some usernames as well.
Just send an email to all users, saying the ones who hasn't been active since idk 2017 or something like that will get deleted. Then people who hasn't been active gets a choice to log back in, maybe stay because they like the redesign of the website or something (which makes more people active) or they won't, and we'll assume they've abandoned their user. Unobtainable items the users had can then be redistributed with auctions (if inflation and too many credits or pd are around) or used in different competitions. If it's just redistributing items this way, then it wouldn't really be bad for online users with the same items either, because it could as well have been the users logging back in, hosting a competition or selling the item and then deleting their user.