when you start adding in the needs of larger organizations, separation of duties, and even the need to not only use the exact same pipeline for many repositories, but provide a governance model over that pipeline then you can start seeing how Jenkins really is better.
The problem with Jenkins is that it’s hard to manage and scale and backup, let alone be kept up to date with all the cobweb of inter-dependent plugins any installation tends to accrue over time.
https://www.reddit.com/r/devops/comments/p5x7c1/guthub_actions_vs_jenkins/