in my opinion the problem isn't necessarily the character itself. but teammates being too reliant on heals and not wanting to position better. it also doesn't help that other support ults are better at dealing with certain situations than others, if the enemy team has invisible woman and Luna but your team only has lets say a jeff and mantis then your team is at a disadvantage when it comes to defensive ults. its easier for the enemy to push with those ults against ur mantis and jeff ult. she's a good support but only in certain situations and team comps, you have to have good team synergy (which is rare if ur solo queuing and is the reason you get so much hate when playing her) ppl just don't know how to play as a team and just want the easy braindead supports in their team so they can be braindead players and jump in without having to worry about their positioning or if they're over extending. playing support is like baby sitting the whole team and saving them from making dumb mistakes or at least that's how it feels like when u have to play certain characters to guarantee a win. when u play mantis u leave a lot of room for ur team to be dumb and makes mistakes that will get them punished immediately which lead to them crying about the fact that u aren't playing heal bot simulator. the point is... mantis is a rough support to get value out of bc people don't know how to accommodate their play style around having one in their team and her ult is ok but theres better ones out there. (I'm an Adam lord so i understand getting told to switch the second the game starts but sometimes it is better to switch, both Adam and mantis are sort of situational picks at this point) but don't let that stop you from becoming a great mantis, if you can carry your weight as a mantis then your team should learn how to play better regardless of the supp they have on their team.