Gary Varga (in editorial)
Of course, doing neither may be a valid option. For example, if you are working on a technology that is not changing in your environment, your job appears safe and you are retiring soon, then you may feel that there no longer is any benefit to develop your work skills. Or maybe you are about to change careers.
I couldn't survive without learning new things. All my life, I've been learning new things. If I ever get to the point where I feel there's no benefit in developing my work (or maybe now that I am mostly retired, non-work) skills you can put me in a box and bury it, because I won't be me any more.
So I believe that training (or some other learning mechanism) is essential. I guess that looks like disagreement with the editorial, but I suspect that Gary actually believes that too.
Anyway, although it's not directly relevant to the editorial, here's a rant/narration/diatrivbe about traing/learning as it has been for me:-
Since I finished my degrees, it's been a mix of training, participating in (sometimes running) research projects, reading up on stuff that looked interesting, learning by trial and error on stuff I'd not done before, sitting around and drinking and talking with people who were expert in stuff that I wasn't, going to seminars and conferences and flapping my ears and/or getting into arguments, getting drunk at lunchtime with colleagues and discovering how the technology they were developing/using worked (or didn't), and many strange ways to learn things that enabled me to do a better job. That learning covered managing things and managing people as well as understanding requirements and designing things and research and building things, delivering things, supporting things, improving things, fixing things when they were broken, and knowing when not to fix things but replace them.
But learning things that are valuable to work isn't restricted to technical stuff and straightforward management stuff. There are other things that can be useful to learn. For example I was trained about behaviour modification, and although I'm still not sure about the morality of it in some circumstances there have been other circumstances where I have been glad to understand the concepts and use it.
I also learnt a bit about office politics: not enough soon enough, sadly, and I ended up learning a lot about office politics working for a couple of years in a company where office politics wrecked the company and if I'd been a bit more educated about office politics when I started (or indeed if my boss had been) the company might have survived a bit longer. That made me realise that even learning how office politics can be played may be valuable to my employer. And it also became clear that what drove that office politics was motivations that I knew about from my management training and it was a failure of that training or of my understanding that I didn't spot what was going on - I feel rather guilty about that, I should have learnt better.
Other highly non-technical things, like being able to speak several languages, were useful too - for example one of my employers decided to get me advanced training (using Manchester University courses) on business French, because my French was already fluent but didn't cover the business aspects; working with Germans wasn't a problem because they could use English for work as long as I could use German for social stuff; my Italian was hopeless (and it still is, mostly), but it was worth learning a bit more because showing an improvement made Italian partners in international projects feel that I was showing them respect by trying to gain better command of their language, and that improved collaboration no end.
So there's something else where I think the editorial has it wrong - traoning/learning doesn't have to be about technology to be relevant to the job, and there are many non-technical things that can be relevat to almost any job.