Is there a knowable "right" value? What should it be now? Otherwise this sounds like a circular "no true Scotsman" situation.
When money is free, it leads to very destabilizing dynamics such as elevated PE ratios and currency volatility.
You mean like... now?
Banks, non bank financial institutions and individuals are free to choose what interest rates they set, to set interest rates for a sector they thinks is at risk well above market levels or to cease lending activity altogether. The fact they choose to lend at low rates is because market participants are pretty bad at predicting the future and market dynamics encourage cutting credit prices, not because the government forces them to lower rates (it doesn't)
And the reality of banking timescales is that a shortage of capital available at a price isn't a nice little hint to change lending activity, it's a signal that since they can't borrow any more to meet obligations they'd best stop honouring depositors' withdrawals. Which is why we have central banks stepping in to make capital available, and before they did that we didn't have stability, we had a lot more ordinary people losing their savings to bank failures and more volatile business cycles.
Yes, the base interest rate acts a floor on interest rates (individuals and banks are entitled to choose to lend below the Fed funds rate. It just unprofitable to do so. It would be even more and profitable to do, so if the Fed didn't exist). They don't set a ceiling on it, so market participants do choose their own rates, and are entirely free not to get their risk assessments wrong and lend at too low a rate (which Austrians claim to be the primary driver of business cycles). The herd behaviour to lend money at low markups above the base rate is a problem of market dynamics, not a problem of lack of market freedom.
In the absence of central banks, the banking sector still competed to lend at the lowest rate, was not blessed with any more insight into whether a particular industry had too much capital flowing into it or a particular loan was a bad one, business cycles were still a thing and banks went bust more often.
Perhaps a better society would have higher employment, perhaps a better society could afford for one spouse to stay at home and take care of the kids, perhaps a better society would have lower income disparity, perhaps a better society would have more innovation, perhaps it would have more ecological conservation. It's impossible for a single economic lever to square the circle on all of those outcomes for everyone.
Free markets are "one dollar, one vote", as compared to government which is (nominally) "one man, one vote".
The other half of your premise is also completely mistaken. Voting power is not linear in number of votes you get.