The thing I don't get is that the federal funds rate was also being raised in the mid 2010s, yet there was no corporate freakouts

Look at the chart you linked to - the fed raised rates from effectively 0 to ~2.4% over 3+ years from 2016-2019. That has absolutely nothing in common with what's happening right now, where the fed went from 0.3 in April to ~3% today.