Fighter Class Melee Champions with Survivability and Rek'Sai

Shields:

In-combat Healing: (reworked irelia) (Rhaast form and E shadow step) (minor Life Steal and Spell Vamp) (a bit of Life Steal)

Bonus Health Gain: (upon regaining Skaarl)

Increased Armor/MR and Damage Reduction:

Unique Defensive Abilities: passive parry parry (reworked Irelia) parry ult passive ult invis ult wall

None of the Above:

Yes, you can heal from her passive during a fight but it's never worth it. To access the full heal you must stay burrowed for 3 seconds and you gain no defense as well as disarming yourself during that time. The heal is incredibly small in comparison to the damage you'd be taking. It was obviously designed for healing after combat. Therefore she has no in-combat healing. You could count her ultimate's brief period of untargetability as survivability but similar abilities on other champions like kayn are far superior in that regard.

It's always bugged me how rek'sai can be such a sitting duck with her relatively low mobility and have nothing to help her stay alive. It forces you to play almost like an assassin and be very picky about when to go into a fight because if the enemies don't die fast then you will go down very quickly. Some times you'll have to ult early just to stay alive for a bit longer and waste the damage on it. I'm curious about why rek'sai doesn't have these elements of survivability while all the other fighters do. Is she too mobile, have too much utility, or do too much damage compared to the others? How come Warwick gets both a crap ton of healing and damage reduction on top of that? Assassins like Rengar and Kha'Zix have healing but Rek'Sai doesn't...

TLDR: Rek'sai is too squishy for the damage that she deals which falls off significantly once late game rolls around. Her strongest time is laning phase because her damage is just right and she's a good early game ganker. Once people start grouping there's not much she can do. The idea that this is totally fine and you just have to end the game early is more like playing around the problems of the champion itself. There are other junglers that are good early game gankers and do well in the late game as well. Rek'sai isn't so busted early that it's why you should pick her. She's ok compared to them.