Linux certainly has project management, bug tracking, and lots of infrastructure. What it famously rejected were inadequate centralized systems that break the way kernel developers and maintainers actually work. Before the tools were there there already was a large human-operated distributed management system that ran on top of email. A lot of linux project operations are still a large semi-automated distributed management system that runs on top of email. It's gotten somewhat more centralized now, as a single source of truth is very useful for tracking bugs, but just because there's a single root to the tree of maintainers doesn't mean it's a a project run by Linus alone, and just because it's not using jira or gitlab or whatever the flavour of the day is doesn't mean it has no project infrastructure.