Assists don’t count?

As someone who is trying to get better at the game, can someone explain why some people disregard assists? This obviously comes up when the team is losing but so many people will mention the kills and deaths but completely disregard assists when complaining about players. I just don’t get it especially when playing a support character. I’ve also had games where I’m doing majority of damage only for my kills to get swooped so then my ratio looks off. Anyway, just wondering if anyone has thoughts or opinions!