[crdoconnor]

>Using the language in idiomatic ways and knowing the most useful libraries and frameworks does take more significant ramp-up time.

Yeah. As in years. This stuff also changes all the time so requires perpetual learning.

>But languages? It's a mere tool, and you need more than one in your toolbox.

It's not a mere tool and languages are more than just trivially learned syntax. They are the umbrella under which a panoply of tools, approaches, ideas, priorities and culture aggregate.

Sure, you specialization isn't necessarily always the optimal approach and sure there are benefits to the cross fertilization of ideas across community lines. However, being a jack of all programming languages, master of none probably means you'll suck more than a specialist at a lot of stuff.

Moreover, some ecosystems plain suck and avoidance is the sign of a good programmer. Statistically, you're probably a worse programmer if you've used a lot of PHP and better if you've learned rust/F#.