They have recently killed off on premise offerings, it's cloud only now. And this makes it harder to trust both the security and integrity of your data.
The fact that a single bad script could delete 400 of their customers should be absolute proof they do not have the processes in place to be a steward of your data in the cloud. On-prem or bust.
On-premise just means that your overworked IT person is going to spend 5% of their time keeping your service maintained, at no point gaining any more than baseline familiarity with the product.
On-premise isn’t a magic pill guaranteeing 100% uptime and 0 data loss.
While on-premise may be a good choice in many cases, it’s not like running on-premise business tools has no risk associated with that choice.
Remember that the goal of a company is to sell the most product possible (output) with the lowest cost possible (input).
Any Joe off the street starting their own business can pay Atlassian $0/month for up to a 10 users. On-prem doesn’t compete with that.
On Prem means you have control over spending. I calculated that if we've moved to the cloud, we would pay YEARLY as much as we spent on Atlassian licenses in last 5 years. That easily pays for the maintenance overhead on our devops team.