Once you've reached the interview stage, it's mostly (or entirely) about fit and personality as you note. But you have to clear the application/resume hurdle before the interview can happen. Generally speaking, candidates are judged on the quality of their resume and you'd be shocked how bad some resumes can be, even for high-level professional individuals and positions. Putting in the effort, while often times consuming and perhaps sometimes unnecessary, puts your best foot forward and does make you more attractive as a candidate to get to the next stage in the process (e.g., screening call, virtual interview, in-person interview, etc.).
Also, with it being so easy to apply broadly online, it's a lot harder to stand out, especially given the sheer number of applications the HR team is wading through. Not to mention an organization might (foolishly, in my opinion) use keywords in its application tracking software to reject/screen candidates before the resume ever has a chance to be seen by a human. Putting in the work can help you stand out and avoid the auto-rejection.