Social Media can be useful if used properly. I personally occasionally use Facebook and LinkedIn (if that counts as social media). I also have an Instagram account which I used once last year, only to superimpose a face onto a celebrity's video as a comedy joke. I've not used it since and have no intention of doing so at this point.
Facebook can be useful for buying and selling goods locally - and I'm a member of some groups on there like Bristol City Till I Die, as well as some historical groups I'm interested in and some Spanish and Gibraltar groups - I sometimes find it interesting to read the various contributions to these groups but VERY rarely post myself.
As for abuse; I'm pleased to say I've not experienced any directed at me personally - and I've never posted abuse either. I've seen some furious exchanges taking place on some of the groups - but with the facebook groups it works very similarly to on this board, in that there are Mods who police it and act on complaints. They remove/ban people who contravene the rules and that's job done.
I understand the suggestion that the victims of abuse should simply delete their accounts, but I also understand that quitting the Social Media platform where the abuse happened would be handing victory to the abusers. Really, those platforms should be policed more effectively so that the instigators of the abuse have THEIR accounts deleted and are subsequently prosecuted for using a public forum for inciting hatred - just as writing a racist slogan on property would be.