A lot of comps work, I don't make suggestions at the start anymore. If we aren't progressing then I start talking about what might help, usually it is just getting people to group up.
If the team has 2 flankers 2 healers doesn't help much because people are too spread out, maybe that is why at the high level they go 2 support because they are always attacking together.
Support isn't just about healing though, it is what they bring as far as their ults and other abilities, with zen discord nerf, and lucio speed nerf more options opened up.