According to their Q4-FY2020 earnings report, they did $2.5bn in revenue from their systems segment last year (which includes IBM Z, Power, and OS's). But their most important segments are Global Technology Services ($6.6bn revenue) and "Cloud & Cognitive Software Segment" ($6.8bn revenue). GTS is cloud infrastructure + support, while C&CSS includes "Cloud & Data Platforms", "Cognitive Applications", and transactions processing platforms...
I'm not sure what exposure the commenter has had to IBM, but it's a bit of a culture shock to hear someone saying they're not important.