New players who haven't read rules is a huge waste of time and is equal to spitting in our faces, but they're far from the only problem this rule solves. There is unfortunately no substitute for it, but it solves so many problems it doesn't matter. We chose 30 posts because it's extremely easy to get it by posting usefully, and I can promise you we won't lose any activity whatsoever.
There is nothing offensive about a rule like this, and claiming there is is laughable. Almost all groups that require membership have a trial period or even formal tests. This is socially accepted in all societies and usually even expected because it undeniably increases the quality of the group or project for all the other participants. For the sake of all players and all volunteer staff, this is an obvious rule to introduce as a community grows larger.
The fact that we've had tourneys completely open for a long time is nice, and it used to work. It doesn't anymore, as the community grows and hacking attempts become much more common. Until you have full knowledge on what's required to organize these events, I advise you not to criticise. Especially harshly, as it's a huge insult to hard-working volunteers that have thus far endured hell to get the events done.