Spammers don't care, their whole deal is sybil attack. To be clear, I have no idea which side of this whole debate I land on. I strongly resonate with @Bitcoin Mechanic's argument that bitcoin is money and should be treated as such. But I also see the point that accurate mempools help with fee estimation, and we can't stop spam in any way other than by forcing spammers to pay for block space. Getting rid of the segwit discount seems like a clearer win to me, but the cost of putting things in OP_RETURN is much fairer and has obvious uses.