Before the death of this we had it where only explosions could kill use, but sadly now it seems that Rage and quick thinking won't activate at the exact same time... Meaning its use almost non and far from an immortal build.
USELESS?! It's no longer an EXPLOIT, but it's by no means useless. It converts all the energy that you usually so preserve with efficiency into a shield that is more potent than maxed Redirection on a dediated warframe.
Take the shitty Oberon or Trinity, Nekros, Valkyr and whoever else can heal themselves - and Rage\QT becomes same invulnerability. I run an endgame MaxVit\Rage\QT Nekros and my EHP is 2000+, constantly restored by all the globes that I desecrate. Don't have to be a Rhino with 1k hp and permanent skin to survive.
Put this mod on Nova or Loki - voila, don't have to max Redirection to stay alive in case shit blows.
Combine Equilibrium with Quick Thinking for any non-healing warframe - and make sure to play around with your stats(that is - stay below 100% health\energy as much as possible) and voila - every orb is ~100 EHP, 25+25 health\energy+240% of energy into health.
This mod is incredible for people who can get the best out of it. For those who run 30-40 with Rhinos and Trinities - sure, perhaps maxing raw health\shield is a more... comprehensible option.
"this was done on purpose and they meant to do it like this, they only changed it because people without the mod would start crying because others had something they were jelly about"
That might have been the case that it was indeed on purpose, but the devs probably observed how it was used in practice and decided that it wasn't the way that they wanted the game to be played. Devs decision. It didn't ruin the game unless you really enjoy playing with setups that the devs decided were overpowered.
Probably because using that combination was a crutch for not playing the game in how it was intended to be played? No game should have immortality, they just removed a method of nearly obtaining it. It was total crap anyhow and didnt belong.