they don't allow VPNs
Most likely to reduce the risk of ban-evading cheaters/griefers. Plus that most people usually avoid using a VPN when playing such games, due to the risk of increased latency.
For some reason, my steam ID wasn't banned.
All of these plugins initiate only an IP ban, so the person is able to rejoin with their "real" IP address.
But you've actually tried asking for your Steam ID to be whitelisted? Shame that their admins don't know how to/don't want to do it.
Many think that Windhund/vinthund is referring to wind (sighthounds are fast), but it's most likely folk etymology. It's believed the name most likely originated in lower German from the Wends - as sighthounds were mainly known from that region at the time.