Based on what are you saying it is the most powerful tree? I feel like the word "universal" is doing most of the heavy lifting in this claim.
Either way, you don't get the same damage, you get less. We are getting halved on dice and a 1/3rd increase on RP scaling. It would be like if I took half your money and then paid you 33 cents for every dollar you had left. You would end up with 66 cents for every dollar you started with (1 * 0.5 * 1.33).
What we're being told is that if we redesign our builds by taking AP out of the tree and go elsewhere we could make up that imbue damage somewhere else. It's all opportunity cost, I have to give something to get something.
This is why having Inquisitive give 5d of imbue damage for 23 points and then ask for 18 AP more for another +2 make it important to look at the value those enhancements and cores are offering otherwise. They have to be compared with what else is out there.
Nothing I suggested is a full value for value replacement, core 4-6 are supposed to be the payoffs (5/6 in particular) for sticking with a tree and really investing in it.
It's literally the worst place in a tree to take away and give nothing back. It requires the heaviest investment to reach and is supposed to be the big payoff.