Why are banks giving loans instead of taking equity in U.S. startups right now?

Airbnb closed $1 billion in debt from U.S. banks, and a number of other startups are finding, when out looking for new investors, that while there is a tepid market for new investment, banks are offering debt instead. Isn't this backward? Shouldn't it be harder to take out a loan than to get an investor? Isn't there more risk and less upside for someone to give a startup a loan than to invest?