The best marketing hire I ever made did no marketing. She spent her first two months fixing how leads were recorded, which sounds like the least interesting work available and turned out to be the reason everything after it worked.
Before she arrived we were arguing constantly. Sales said the leads were bad. Marketing said sales was not working them. Both sides had a report. Both reports were internally consistent and mutually incompatible, because they counted different things and neither team knew which things. We spent more energy litigating the data than acting on it, and every new campaign added another unreliable number to the pile.
Adding a marketer to a team that cannot measure itself adds volume and noise in equal amounts.
The uncomfortable truth is that most marketing teams are not underperforming, they are unmeasurable, and those look identical from the outside. Somebody senior eventually concludes marketing is not working, which may or may not be true, and the org cannot produce evidence either way. That is a solvable problem and the solution is a person, not a platform. Tools do not fix definitions.
What that hire buys you is the ability to be wrong on purpose. Once the pipeline is instrumented you can run a bad quarter deliberately, kill a channel, watch what happens, and know. Without it every decision is a matter of opinion, and opinions get settled by seniority. I have made this hire first at two companies now and I would not run the sequence the other way again.