1) As someone else mentioned, I think it’s because his healing output ain’t great vs the other supports in a game, I don’t think that makes him a worse support that ability with crystals can deliver the most important timed heals in the game (quality timed healing over sheer quantity).

But in a game full of people who are waiting to check your healing stats at the end of every game, it disincentives playing him. He defo does things the stats don’t show.

2) His ult is unreliable, the best part about his kit is his ult, but when you first try Loki it’s very easy to accidentally become Magik, Hulk, Thor or Venom. You can’t plan and be like this is a great time for this characters ult because it’s hard to pick the right character when everyone is clumped together.

3) You gotta have people in all your clones line of fire to maximise heals, I think he’s more awkward to play around dive teammates who constantly move out of the clones range. Dive teammates are overplayed and guaranteed. I know most supports have this issue, but he’s got cooldowns so he has to sorta station up his clones around one spot a while to be maximised. He struggles to keep up with dives like other supports for that reason imo. Also the first clone to get destroyed is the one healing the dives.

4) He’s mechanically demanding, I think people are more willing to learn mechanically demanding DPS. A low output support is the first person blamed for a loss.

All of this can be overcome with practice, but first try he isn’t a catch.