Ask yourself why there isn't more welcome bots, after all Steemit and Hive have been around for a long time.
Bots that blindly greet all users with no intelligence have never been welcome in Hive (or Steem)
The original bot that did this was Hive account@wang.
@wang

It's been flagged down to -10 rep. You don't know the history. There is nothing new about this.
Your bot serves to advertise your witness, what if all top 20 witnesses did this?