Why does everyone's phone suddenly say we need hundreds of packages of tortillas? Why am I being reminded to do things for a job I left years ago? And you suddenly realize there's a design constraint and no one has designed for this and the app starts misbehaving terribly.
Well the obvious answer is to stop using Apple reminders. But instead, I wrote some AppleScript to automatically delete old reminders. It works well enough that I forgot it existed until I happened to look at crontab for another reason.
set monthago to (current date) - (30 * days)
tell application "Reminders"
set myLists to name of every list
repeat with thisList in myLists
tell list thisList
delete (every reminder whose completion date is less than monthago)
CrontabJacks-MacBook-Pro:bin symlink jackcoates$ crontab -l | grep purge
20 20 */7 * * osascript ~/Library/Mobile\ Documents/com~apple~ScriptEditor2/Documents/purgeoldreminders.scpt
Jacks-MacBook-Pro:bin symlink jackcoates$