not when you start to have too many tools.
part of your value is being experienced in a language. you can't do that if you are spread thin amongst too many.
As a 50-year-old, I'm inclined to agree with the statement that there is such a thing as too many tools, but not for the same reason. Expertise and experience are important, no question about that. But both are often easily transferred from one language or framework to the next. For my part, I'm quite enjoying working with NodeJS, Angular, NoSQL and a bunch of things that take significantly different approaches to problems I've been solving my entire career.
But a problem I face quite often these days is trying to apply the toolkit approach with newer software. On any decent POSIX-supporting platform, you can generally leverage libraries and modules for just about anything and still expect at least a modicum of consistency. Each tool has its own quirks and foibles and strengths, all of which need to be understood, but with a bit of time and perseverance, these can be coped with.
But the application I'm working on right now requires the integration of an Angular framework with UI elements derived from JQuery, D3 and Bootstrap as well as one or two products of the inspiration of some young developers who are clever but sadly too confident in their own abilities. Trying to reconcile them all has resulted in a LOT of time spent pondering, refactoring and coping with bugs that inevitably result from using the tool in a way that wasn't foreseen by enthusiastic but inexperienced developers.
So far, the benefits have outweighed the costs, but there's a fine line between saving time by appropriating others' tools and wasting time shaving a very big, hairy yak.
I like many of the new technologies I'm using, and I love learning new tricks, notwithstanding the few grey hairs remaining on my shining dome. But yes, there is such a thing as too many tools. And many young developers these days are going to have to learn that the hard way.