Conventionalism means that we don't make the same mistake twice. There is a learning process with respect to conventional weapons. But, with two exceptions, weapons of mass destruction were not used. In this century, if wars continue in the way which they have in the past century, it is very probable that mass destruction weapons will be used. We must move to eliminate nuclear weapons.
People say that it's too hard.
You can't disinvent them. You can't put the genie back in the bottle. That is wrong. The genie can be put back into the bottle. Time doesn't permit for discussing how it can be done.