Demoted on a S+?

Is there no mercy in this ranked system, for me to just reach 0lp, and then lose on an S+, and still get demoted? Better yet, this is my 5th time being demoted in this similar fashion (Granted I havn't ended on a S+, but on good matches). I truly believe that demotion should be based much more on individual score than just losing the game. That match I had a rek sai with 919 ping and just ended up feeding, blurred his name for confidentiality purposes. Did I deserve to be demoted in this way? Is this a problem within higher up ranks? Maybe I'm just whining? I don't know.
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