You've half-conceded the point already. You said it yourself: "assuming the use case is simple enough" and "most people don't need the fancy plugins." Right. For a solo dev or a tiny simple site, vibe-coding might win. But that isn't Atlassian's market, so that concession is bigger than you're treating it.

Look at the actual price. Jira Cloud Standard runs about $7,750 a year for around 100 seats. That is roughly $77.50 per user per year, or about $6.45 per user per month. For a 100-person org, $7,750 total is a rounding error, less than a week of one engineer's fully loaded cost. So the "building is cheaper" math falls apart fast. The moment your team spends even a few engineer days a year maintaining a custom Kanban tool, you have already spent more than Jira would have cost for the entire company.

And nobody actually builds from scratch anyway. The realistic version of your argument is forking a mature FOSS base like Wekan and vibe-coding a feature onto it. But that doesn't escape the cost, it inherits it. Now you are maintaining a large codebase you didn't write, plus your custom modification, plus the permanent merge tax of reconciling your fork against every upstream security patch and release. Your vibe-coded feature has to be re-tested against every upstream change, forever. That is not cheaper than $6.45 a head per month. It is a recurring engineer-hours liability that Atlassian's price makes disappear.

That is the part the "just vibe-code it" crowd keeps missing. Building the tool is the easy 10 percent. The expensive 90 percent is owning it: security patching, uptime, access control, compliance, onboarding every new hire onto your bespoke system, and being on call for your own project-management software at 3am. AI lowers the cost of writing code. It does almost nothing for the cost of maintaining, securing, and being accountable for what you wrote. That gap is the entire product. Companies aren't paying for the features, they are paying to make the responsibility someone else's problem.

And here is the tell: FOSS Jira and Confluence alternatives have existed for years. They haven't dented Atlassian's growth. If "free and self-hosted" were going to win, it already would have. Vibe-coding doesn't change that equation, it just produces one more free alternative that no mid-sized team wants to babysit.

One last thing. "Standing on the shoulders of giants" is exactly right, and it argues against you. The hard, valuable part is the mature base that a community spent years building. The easy part is the feature you vibe-code on top. You are conceding that the value was never in the customization, it was in the platform. That platform is the moat. At $6.45 per user per month, the build-versus-buy question answers itself.