The goal of pre-commit hooks is to improve the quality of commits. This is achieved by making sure your commits meet some (formal) requirements, e.g:
that they comply to a certain coding style (with the hook style-files).
that you commit derivatives such as README.md or .Rd files with their source instead of spreading them over multiple commits.
and so on.
As all changes enter a repository history with a commit, we believe many checks should be performed at that point, and not only later on a CI service. For example, creating auto-commits at a CI service for styling code creates unnecessary extra commits, as styling can be checked at the time of committing and is relatively inexpensive.
Implementing hooks in a framework such as pre-commit.com has multiple benefits compared to using simple bash scripts in .git/hooks:
Easily use hooks other people have created, in bash, R, python and other languages. There are a wealth of useful hooks available, most listed here. For example, check-added-large-files prevents you from committing big files, other hooks validate json or yaml files and so on.
No need to worry about dependencies, testing, different versions of hooks, file filtering for specific hooks etc. It’s all handled by pre-commit.
Hooks are maintained in one place, and you just need a .pre-commit-config.yaml file. No need to c/p hooks from one project to another.
Have an idea for a hook? Please file an issue.