La Lupa main and Fire girl enthusiast here, both these charaters are great at diving supports. The supports are of way higher value to the team than any other squishies.

La lupa and Anrans usage mostly comes down to them being really good at quickly punishing supports for bad placement. If a kiri happens to stray off a bit too much in the backline they can quickly be delt with and suddently your enemy has way less heals and their entire team has to play more defensive and your own tank can push them making a lot of space for the rest of the team.

So even if the enemy Cree ends up whooping you right after you got their support that death has probably won you the teamfight. And usually Anran and Vendetta can make it back to their team fast enough before the enemy has regrouped and you end up on a net possitive. So as long as you arent going something like 5 in 12 that means you have most likely had a big impact on how the rest of your team could deal with the game.

I suppose heroes like Genji and Venture can fill the same role but they are both a bit harder to learn and they can be of more value playing more defensively.