While 30 days sounds extreme, I’ve got plenty of warnings in the past 25 years from sites which wanted, and did delete my account because I didn’t visit their site in a specified timeframe, like half a year, or a year.
I got one from Discord a few days ago. I didn't check if it was real or phishing, and I didn't check my password manager. I can't remember why I would have created a discord account so I'll let it go. Maybe I was self squatting.