The idea behind core inflation as a measurement is the same idea behind the bureau of labor statistics as a measuring entity.
After the end of the Continental currency in 1792 the United States experienced very little inflation until 1973, except for the fiat money war inflation of 1862-1865. So, things had deteriorated into a situation where fixed incomes from government pensions were prevalent, and a progressive-rate income tax was in place. When inflation hit in 1973, and persisted, largely owing to the Nixon administration breaking the last link to gold in 1971 combined with a terrible foreign policy that led to the Arab oil embargo, the country was set up for a great deal of suffering. The people who suffer the most from high and persistent inflation are those who have fixed incomes; those with low pay and little opportunities for mobility; and those who pay taxes on income. So, just about everyone had reason to complain.
To address these issues, the government established "cost of living adjustments" on the amounts paid out to pensioners. It also established adjustments to the standard deduction, the exemptions, and the rate tables for taxation. Doing so addressed the worst problems. Then the country became used to inflation. It has persisted ever since.
But, of course, one of the things about mankind, as Dostoevsky pointed out is, "they are such scoundrels, they can get used to anything." And, one of the things most people have gotten used to is being told what the rate of inflation is by the government. In fact, the government is a highly interested party in the number it reports, because it uses that number to increase payments to Socialist Security recipients, it uses that number to adjust tax payments, and even rate tables are affected. So, the government is motivated to report very low inflation. So, they lie.
One of the essential lies that the measurement of inflation published by the government represents is the definition of inflation. Inflation is not fluctuations in prices, and it never has been. The usage of "inflation" to mean an increase in the prices of things is mistaken. It may be widespread, but it isn't the root cause. And, if we don't strike at the root, we shall forever be hacking at the branches of evil.
Inflation is the increase in the supply of money. In other words, inflation is caused by the policies of the Federal Reserve System which is a branch of government, though it is largely controlled by private banking gangsters (banksters is a term I'm very fond of; wish I knew who coined it). Right now, today, I believe the broadest measure of inflation, the M3 money supply, would show about 12% to 14% inflation, if it were still published. Shadowstats.com is a site you should visit if you want a different look at this statistic "inflation."
EC Riegel, writing in 1949, noted that the inflation of the money supply perverts everything about the free market economy. Every contract written in dollars is dependent on the whims and psychoses of those in government for the meaning of the term "dollar." And, of course, the value of the contract is perverted by the perversion of the value of the dollar.
Riegel wrote, "The state's modern method of deceiving the citizen
with counterfeit money menaces civilization through a confusion
of monetary tongues and renders society unfit for self government
until its ignorance of money shall be dispelled and government
of government restored by the separation of money and state."
Separating the issue power of money from the state is a key tool in the fight for individual liberty. After all, your freedom and sovereignty over yourself are inherent within you. Etienne de la Boetie pointed out that all you need to be free is to declare it.
"To desire freedom is an instinct. To secure it requires intelligence. It must be comprehended and self-asserted. To petition for it is to stultify oneself, for a petitioner is a confessed subject and lacks the spirit of a freeman. To rail and rant against tyranny is to manifest inferiority, for there is no tyranny but ignorance; to be conscious of one's powers is to lose consciousness of tyranny. Self government is not a remote aim. It is an intimate and inescapable fact. To govern oneself is a natural imperative, and all tyranny is the miscarriage of self-government. The first requisite of freedom is to accept responsibility for the lack of it." - EC Riegel, 1949.