I feel like this is the case regardless of the system? You can't just install a "Good" leader once and expect them to provide everyone with equal rights forever. You can't even build a "Good" system once and expect it to provide you with rights by itself. It would still require well-meaning, educated, active, and organized constituents to continuously stand up for what is right, prevent corruption and abuses of power, etc.
There are no physically inalienable rights. They are ultimately just ideas and not laws of nature, and thus require enforcement by some human persons, and any such person is subject to corruption by power.
There are no infallible systems. Social systems are but humanly devised constraints, and humans can and will overstep those constraints. It takes other humans to reinforce the system and maintain the constraints.
That said, the system of capitalism is obviously a shitty one for everyone but the top 0.1% (and this percentage decreases with time), we as a species should do better. Socialism isn't perfect either, but at least it empowers much more people to be active participants rather than slaves.
To reiterate, it is simply not possible to "build a system in which no one has the power to take away to begin with". Socialism would still be subject to corruption (as evidenced by countries that instituted it) and require constant "upkeep" by the citizens. However, socialism tends to produce citizens more well-equipped to protect their rights.