I've played several Imperials over the years, and had more than one Emperor (and Anathema).

I get what you're saying. Being an Anathema can really suck.

But here are a few reasons that the current system works:

Effort vs. Reward
A common refrain in IMMland is that Empire is "easy in, easy out." You can get inducted into Empire and access to basic sect powers using a completely automated system, without any vetting from anyone.

You can then get promoted (and gain access to more powers) with help from any of several people.

It usually isn't very difficult. Getting "Elite" is often a little bit tougher. Getting Sect leader, with its associated strong power and leader con, can be difficult or incredibly easy, depending on the makeup of the sect at the time.

The tradeoff is that it's possible this will all be taken away at any time, so you need to exude loyalty and make yourself useful. It's the one cabal where players really are in control (within certain, broad boundaries). It's a unique dynamic - the dark side of the free market in CF.

Anathema Is Not The End
If you're a powergamer who made a character with the sole intent to use Empire numbers or powers to gank everyone or explore hell, then yeah, maybe this would ruin your character. But you have only yourself to blame. Anathema has been part of Empire literally for decades, so you've always been on notice. Maybe the problem isn't the cabal - it's that your goals are too narrow and rigid.

But here's a concept I want to impress upon you: Anathema is not the end. If you see your character as a story, you can use the experience to develop it.

You can become a bitter exile or an active hunter of Imperials. Some Anathema have come back and become Emperor. It's not without some risk, pain or effort, but it can be fun if you allow it to be.

There's even a religion that is partially devoted to people like Anathema. *shameless plug*

There Are Alternatives
There are other cabals (or even uncaballed roles) that can accommodate exploration just as well - if not better. Another cabal, in particular, has a power that in my opinion is absolutely unrivaled for exploration.

So if Anathema worries you so much, why don't you just go elsewhere?