They are, the argument that the poster above you put forward is such a tired argument and I really do not understand why people are trying to hide the fact that the Fed is actually creating money out of thin air and buying assets from banks for it. The Fed doesn't technically "print" the Federal Reserve Notes, but for all intents and purposes it is legitimately money that is being created, only digitally. You are entirely correct in your assessment that they are manipulating the market by being an agent with unlimited amounts of cash and can therefore provide options for banks that they otherwise wouldn't have in a free market.

Also bank reserves can be used as collateral for further loans, just because you don't lend out the actual reserves doesn't mean more money isn't being created, it's just done in a roundabout fashion.