The USA is not a democracy, it's a Constitutionally-limited republic. The reason for the House of Representatives (i.e., your "middlemen") isn't to prevent mob rule, but to recognize the simple practicality that there are too many people for a direct democracy to be workable. The Senate
is there explicitly to block popular rule, it being a compromise to States' Rights.
The most important thing about the government of the USA, and the thing that serves to protect the minorities, is that the federal government is limited to a short list of explicitly enumerated powers (see especially Article I Section 8), and may only wield those in ways that respect the Bill of Rights.
And thus, every time someone advocates that the federal government take action that is not in that enumerated list, they erode those protections further.
Today, a few items in that enumerated list of powers that aren't very specific, especially the "interstate commerce clause", have become gaping breaches in our Constitutional protections, allowing our government the de facto power to do damned near anything it wants. If you're interested in protecting the rights of the weaker parts of society against abuse by the majority, the place to look is toward shoring up those abused parts of the Constitution.
Example: the federal government really has no general police power. Laws such as those under the "War on Drugs" are founded on the idea that drugs could conceivably be sold across state borders (even if they're not, in fact, but are actually grown at home for personal use -- see Gonzales v Raich). By allowing such absurd exaggeration of the definition of "interstate commerce", we've given the federal government license to terrorize citizens, strip us of our privacy, and in the end, give the USA the largest prison population -- by far! -- in the entire world.