I'm sure many users will appreciate it. Is this new restriction/feature actually stated anywhere other than here so users actually know they're already opted out? Wouldn't it be better to allow all messages at first but give a warning with PMs from newbies such as something like "Find this message annoying? Go into personal settings to block messages from brand new/newbie accounts" etc?
This is very true, because some users might be unaware of this new policy or what do I call it. So like you said, if it is been done this way, like to give some excuses at first,then follow by taking the necessary action later.
But as for me, it will be better this way, because some newbies may be trying to get access to you privately because of one reason or the other , if we newbies are been banned from private PMs it will be very difficult for us to grow.