OK, go back to the last economic turndown.
At its bottom, there were a lot (note careful use of qualitative terminlogy) of people in bread lines, and a lot of empty offices, idle machinery, etc. (“unused capacity”). So, as the economy improved, the previously jobless could be employed for little more than the cost of pulling dust covers off things.
Now, all of that unused capacity is, eventually, used. Then, when people are to be employed, office buildings must be erected, machines must be built, and so on. Much more expensive. The faster the economy grows, the sooner that that point is reached.
“Inflation” is the quality of monetary momentum (mass of money times velocity of money) increasing relative to the actual amount of goods available. To have the wherewithal to create new stuff (office buildings, machinery, etc.), one traditionally goes to the banks, borrows money, creates the stuff, utilizes (rents, sells) it, and pays back the bank. During the lifetime of the loan, there’s a greater mass of money, and the goods to back it with aren’t created until after (sometimes well after) the loan is taken out. Thus, inflation; the faster the economy grows, the higher.
(This, of course, is the extremely simplified version. All sorts of things can cause the inflation not to show up until later. And, of course, the less-simplified version includes government deficit spending, fractional reserve policies, fiat currency v. specie, and yadda yadda).
Now, generally speaking, inflation is good for debtors, but bad for creditors (and anyone with a bank account is a creditor). Also, if and when the economic boom slows or even stops, just as the appearance of inflation can be delayed, so can its disappearance. We experienced this phenomenon under that Carter fellow, back in the late '70s (you may have heard of him from your parents), although the real cause was largely the extremely bogus government policies followed in the '60s and early '70s and Carter, like Hoover, got the blame for what he didn’t cause (although Carter was a lot more snooty about it that Hoover was). Ever since, the powers-that-be have had the feces scared out of them by the specter of inflation, and more so of stagflation (i.e.,, inflation combined with a static or declining economy).
Since there’s no particularly good reason for the economy to grow at a torrid pace (most Americans have evidently decided that they’re rich enough, more or less, and the population isn’t growing that fast), Greenspan and his cronies would like it act sedately.