These institutions clearly have the capability and willingness to digitally conjure "money" from nothing and have felt compelled to remove over $10 trillion worth of assets from the markets since 2009. This swap of illiquid assets for liquid cash had (and continues to have) the effect of squeezing the prices of the remaining assets higher (more money chasing fewer assets=price appreciation).
A prime example of that squeeze, the US stock market total valuation (represented by the Wilshire 5000, below) is $10 trillion higher than the "bubble" peak of 2008...and $11 trillion higher than the 2001 "bubble" peak. Likewise, US federal debt since 2008 has increased by...you guessed it, $10 trillion.
The narrative seems to be that 2009 was a one off event and that the central banks role was and still is to "stabilize" the situation until things "normalize".