Back when interest rates were higher people would open cc's with 0% intro APRs (and no fees for balance transfer checks) and stick the balance into a savings account.
I'm sure some people still do this, but with standard savings accounts at 1%, it's not worth the effort. Now if you put it in a rewards checking account, which can earn 4-5%, then it's a different story. The problem with those is that they're not scalable - they cap the balance that can earn the high rate of interest.
The better comparison is stock market returns, real estate cap rates, etc.
This is why I'm still postponing the complete payoff of my consumer debt, FWIW. Most is at 0%, a little is at 2-4%, and I'm reliably pulling double digits on investments. Right before retiring I'll start putting those returns into a rapid payoff plan.
My partnership is putting half the DP for an upcoming buy on credit - some from a private loan at 6% and some on a 12% LOC. It's all paid out of rents in 5-6mos and the math still works out.
Said smart employer could have a reverse test proving the potential employee's inability to budget. Of course accounting employees would have their shit together...right? Right??
And doctors/nurses never smoke, drink, eat unhealthy foods, do drugs, have unprotected sex, or drive fast? ;)