All of the guilds capable of picking blackroot have had a ban on it, as well as
many other poisons, for some time. Sorcerers can evoke it, but they still need
somebody to pick it for them. Now, it seems competent players usually tend to
find a way to get some small stockpiles of the banned poisons, but they tend to
use them very rarely, because resupply is not guaranteed. So, against certain
professions, mysticism is less useful perhaps. But against any profession? Nobody
other than somebody who can pick blackroot will have the supply necessary to
completely negate all bonding for any reasonable length of time. And as far as
mysticism being less useful against rangers and thieves...well, every profession
has skills that are more and less useful against certain other professions.
Written by my hand on the 25th of Paglost, in the year 1106.