Its not the IT guys themselves, its the aggregate influence. One large school campus flips the switch to Firefox on their next image deployment its a drop in a bucket, but when 1000 schools, 2000 government agencies and 5000 businesses all suddenly stop using Chrome the graph starts to move, because laypeople just accept the default.
IT guys are like browser-influencers, they tell their parents what to use, friends, and so on. We all used to recommend Chrome, I don’t anymore.