An anecdote: I had trouble participating in the Ethereum network properly, but then I synced my timeservers with Hetzner's NTP servers and things resolved. And at the time of writing, around 15% (roughly 500 nodes) of Ethereum nodes on hosting providers use Hetzner (though it seems it is consistently decreasing): https://www.ethernodes.org/networkType/Hosting

The likely reason for forbidding the applications is that syncing deteriorates the disks heavily. Nevertheless, they seem to be widely used to this date, as time synchronisation with them seems to have positive effect on node operation effectiveness.