That if the employer creates a situation where you can't play an hour of guitar at home and put it on youtube without firing you, then it's worthwhile for no valid reason.
That as far as worthwhile goes, that's a pretty low bar. In fact the lowest there is -- where what we do is determined by sheer immediate need and necessity.
To give an example that might sound extreme, but it's the reality for hundreds of millions in other parts of the world (and a decent tens of millions in this part of the world too) a 12 year old child can go work in factories, mines, sweat shops or even prostitute itself to sex-tourist perverts to avoid starving. That doesn't make those "pursuits" worthwhile.
Of course for a privileged or semi-privileged middle/upper-middle class person, on a steady diet of comfortable upbringing, family support, financial support net, cushy jobs, and "do what you love" kind of advice, the situation is probably so alien that what's wrong with it might not even register.