I’m all in for the idea of “tags” instead of “job titles” and was agreeing with the whole text until that phrase:

“the task that is the most relevant and valuable to the
team at that time, within the context of the project’s goals, rather
than just the tasks of most relevance to my job title”

Sometimes, the project goals may be harmful and blind the team to some other tasks that someone “knows” has to be done (like a new tool to analyze some data or the POC of some technology that no one in the team have expertise yet and they may need in the future). A “responsible specialist” may use some “free time” to tackle some of those tasks, while someone “following the goals” would pick up the next Sprint story…

Of course, If the PO is a nice person and the team has a good relationship with him/her, those tasks can be made visible and emerge in the next planning meeting and may even have a higher priority than a Story would In that particular case, the “just follow the goal” approach would work well