Hiring decisions can be touch and often our personal whims and desires make their way into these decisions. If a person looks like us and is someone we think we can be a friend with we are much more likely to hire them. This is where more objectionable methods may be helpful in the hiring process.
An algorithm is a method of using a formula or calculation to determine qualifying candidates. Hiring managers don't need to base the the final decision on these algorithms but could use them to create their final candidate lists.
They don't necessarily need to be complete. It could be as simple as putting together a wish list of skills, attributes and characteristics and using them to weight or rank each candidate.
One then uses these rankings to find their final candidates. The hiring manager then selects that which makes the most sense for their team and department.
A word of caution is necessary, it is better to have someone else conduct the algorithm so that there is some outside influence on the hiring decision.
It isn't possible to find the perfect candidate every time. However, it is possible to improve upon the right hire by allowing more objectionable evaluations into the process. Even with algorithms companies should still consider their "gut" in some of the decision making.