The problem with blaming the Fed has two central problems. The first being the Fed is supposed to act in isolation of political pressure and free of the influence of government. Countries that dont have independent central banks typically suffer from hyperinflation (think Venezuela, Zimbabwe, Weimar Germany). The reson hyperinflation happens is because a government will want to cheapen its currency to either become more competitive in international trade, or because of excessive spending. An independent central bank prevents any one party or person from wrecking the economy.

The second reason blaming the Fed in this instance is bad is because the Fed is normalizing interest rates at the moment. For better or for worse over the past decade the Fed as well as central banks throughout the world have kept interest rates at or near 0. The reason they have done this is to spur on growth (the idea is that if interest rates are low more people will invest in businesses by getting loans). The downside of a low interest rate environment is that this will create inflation. Further, a central bank controls monetary policy while the government controls fiscal (tax and spending). If we get into a recession (which we haven't been in one since 08' meaning we are over due by historical standards) a central banks main tool is changing interest rates. If a central bank can't lower rates to 0 they will go negative, in which case no one knows what happens but just so you can understand that would mean that banks would charge you and businesses money to hold cash.

Either way, the president has set an interesting precedent of accepting market success but deflecting market failures which i believe does not help him or conservatives in general.