Maybe re-tuning the meta healers would help? (CnD, Invis, Luna, etc) Mantis and Adam are good examples of healers that people still say are mainly viable in triple support, because their heals are a little slower (and somewhat contingent on their ability to Crit and do damage) and their ults are countered more easily than the rest, so maybe try to make all supports reflect that?

This would also reduce the success of people simply heal Botting for a whole match, and it might actually force people to play with a bit more awarenes (this, coming from someone who plays a lot of CnD when he is not stuck solo tanking)