Looking at Jira, Linear, and Productboard, I think they show three pretty different ways of entering a market.
Jira entered an existing market. It launched as a tool for software developers to track bugs and tasks, competing around a problem that teams already knew they had. (Atlassian Community) I would consider this a red ocean because Jira had to win customers in an already understood category. The belief was basically that software teams needed a better and more organized way to keep track of their work.
Linear entered by resegmenting that market. Instead of trying to serve everyone, it originally focused on high-performing software teams that wanted something faster, simpler, and less frustrating. Linear itself described the goal as letting teams focus on their actual work instead of spending so much time managing the process. (Linear) To me, this is a patch of blue inside a red ocean. Linear had to believe there was a group of people unhappy enough with existing tools like Jira to switch, especially if the alternative was faster and easier to use.
Productboard feels closest to creating a new market. Instead of mainly managing the execution of work, it created a dedicated space for PM work like understanding customer needs, prioritizing what to build, and communicating the roadmap. (Productboard Help Center) That makes it much more of a blue ocean. Productboard had to believe that product management had become important and complicated enough that PMs needed their own dedicated tool rather than piecing their work together across issue trackers, spreadsheets, and other tools.
What I find interesting is that all three sell to similar people, but they entered that audience through completely different market strategies.
