IBM and Red Hat weren't really in competition so, it makes sense that Linux mostly benefited them. I don't recall ever seeing anyone use an IBM workstation. The only places I've seen them used is for kiosks and POS.
I used one a bit in the mid 90s when I worked for the Forestry Commission here in the UK. It was running a specialist scientific application I can't remember anything about. I only worked on it to get it connected to our network, access NFS shares and connect to printers. It was incredibly expensive compared to the Suns. It had an administration interface that was just a set of bash script menus for running various commands to do basic admin activities. I ripped it off and converted it to C Shell to simplify some stuff on the Suns for some of the less technical staff. That was one of my first moderately complex shell scripts, so thanks IBM.
A workstation is not a desktop PC. I can guarantee you've never seen a workstation used as a kiosk or a POS.