i've managed engineers and data scientists for 16 years and I've hired probably 80+ people with MS degrees. Let me tell you what actually moves the needle on promotion vs. what doesn't.
the cases where the MS actually helped with advancement:
moving into a technical leadership role from a non-traditional background. I've seen this most with people who came up through analyst or ops tracks and then got an MS in CS or data science. The degree credentialed skills they'd already been building informally, and it gave managers (including me) an easier path to leveling them up.
transitioning from industry to research-adjacent roles. if you want to move into an applied research team or a research scientist role, the MS (or PhD) is usually a hard requirement. no amount of 'equivalent experience' gets you past that filter.
getting promoted past a ceiling that requires it. some companies, especially consulting firms and some banks, have explicit credentialing requirements for principal/senior manager levels. at those shops, the MS or MBA isn't optional for advancement, it's table stakes.
when the MS doesn't help much:
staff engineer or senior IC tracks at tech companies. promotion at senior and staff levels is almost entirely performance-and-scope based. I have never once factored someone's MS into a staff eng promo packet. the work is the signal.
management tracks at most tech companies. same story. managers get promoted based on team outcomes, not credentials.
when you're already in the role and have already demonstrated the skills. the degree is retroactively confirming something the organization can already see. at that point it's a resume signal for the NEXT job, not a lever at the current one.
bottom line: the MS is most valuable as an external signal to future employers, not as an internal promotability lever. if you're doing it for a promo, make sure your company has explicit criteria that reference it. most don't.