Because of 2018 operation "Power OFF" but it's still pretty easy to take anything down.
Hetzner has the WEAKEST DDoS protection out of ANYTHING out there - Arbor sucks.
Send me your website url and I'll keep it down for DAYS and whenever you cry to hetzner I'll just fry it again, it's that easy and that's why they're the cheapest - because everyone ran away from them back then.
I run a few websites with moderate traffic (~900K daily page views total) on the same VPS and never had an issue with DDOS. Is this specific to some industries?