My reasons are listed below.
-- Demerit system might put a huge wall between members instead of having a good conversation with others.
-- Letting other members to give demerit to others is not a good idea. There might be people who might give demerit to other member that they dont like.
-- People tends to retaliates when somebody mocks them. So its possible for two members to give demerits with each other until they both loss all their merits.
-- Demerits will add to the difficulty to rank up.
For me this forum is created so that the members here will help each other to grow. Do you agree with me?
Ps. I hope my english is on point,so if you found something wrong you can correct me so that i can learn more.
Simple solution to this problem is to give that privilege only to staff. I also think that merit system is not needed but then I see a thread like this one and I have to rethink. You should express this opinion in already existing thread about demerits. Like these:
https://bitcointalksearch.org/topic/the-merit-system-is-a-huge-success-and-now-its-time-for-demerits-2970478
https://bitcointalksearch.org/topic/not-merit-demerit-is-the-way-to-go-2963600