If a restrictive is not set this normally means "no restriction" like all of the needed permissions or "i_client_max_idle_time". If there is no permission there is no restriction.

But there are other permissions like "i_client_max_channel_subscription" which have to be set to -1 to remove the restriction. If the permission is not set you can only subscribe one channel which is the one you are in. Not setting the permission should set it to unlimited (which atm "-1" does).
Other exmaples are:
avatar filesize limit, download quota. I think there are more but i can't remember.