Guarantee, I agree. Resistance to quickly creating a rainbow table with significant coverage, however, is a reasonable property. The mentioned bcrypt library

Guarantee, I agree. Resistance to quickly creating a rainbow table with significant coverage, however, is a reasonable property. The mentioned bcrypt library allows you to “tighten the ratchet” over time as average computing power increases to make hashing a single password in 2010 take about the same amount of time on average modern computing hardware as in 2020 (assuming you correctly increase the number of iterations)