For your personal development, it offers a structured way to learn a new skill; doing it on your own works, but has the risk of skipping large swathes of it or getting bored with it. Working towards certification is a goal you can work towards, as an alternative to undirected or situational learning.

And for an employer it's a nice tick when assessing candidates, it might just tip the scales in your favors vs someone else. However, I recognize that we're very much in a "seller's market", in that it often feels like education or certifications don't matter when it comes to finding a job, to the point where some years ago, people that just had a crash course / boot camp (as opposed to a formal education, bachelor's or master's degree) could land a six-figure job at a FAANG or startup company.