While I am not a fan of the ban on sliders without a brace and think in time we may find a better compromise there was a reason for the rule change.
For those that have to deal with the change I will remind you there is a huge amount of freedom in how a seat back brace is designed.
I could build and install a legal brace in an hour with a hammer, vise and a piece of flat stock that would not be a spear. If it needed to be adjustable it might take an hour and a half.