I am curious, has anyone actually tried talking to these perpetrators about the problem? Talk as in a friendly chat, not sending hate messages, calling them names, yelling at everyone to report/ignore them, and not auto putting the first bad player you see on ignore.
If these players aren't actually trying and are just sitting there for exp/cxp then it might be worth while trying to help them, persuade them that it's in their best interest to try their best. If you're talking about the bad/new players (most of the whining I see is aimed at them) then you could try giving them advice/tips, help them get better, share builds etc.
I've noticed since 5.0 the toxicity levels in GSF has risen immensely, probably because of the cxp/UC rewards.
another thing, the people that I've seen in chat whining about these "leeches" saying how bad they are, how they do nothing for the team except make them lose faster. Well there are plenty of people that can make these whiners look like "leeches", when a new player faces an average/decent player they will get wrecked. when an average/decent player faces a god lvl play they will also get wrecked (to put it mildly).