I think it's maybe a bit of both? I worked at an org that was using Trac for most things. It's probably fine for a small, engineering-driven company, but it's not very full-featured and isn't great for PMs and other business types.

So once the company got large enough, management wanted to switch. Many of us essentially said, "ok, that's fine, but please please please not Jira". And yet, they went and hired some consultants who were like "oh, Jira is the industry standard for your line of work, you'd be taking on a huge risk not using it, blah blah blah". Management bought it, and they've been on Jira ever since.