Alright, I will.

> One kind of bad hire is the technology-lover who values their own preferences over the needs of the business.

OK. This is not a mutually-exclusive relationship. One can prioritize both of these; the best team player will prioritize the needs of the business (and the team) more, however. This to me seems like you're really addressing the problem of "vanity/primadonna devs" who are not team players, and not just devs who really like certain technologies which will possibly blind them.

I also think experience tempers this quite a bit. I've certainly had dev experiences where I became enamored with an idea or trendy tech, felt I absolutely had to implement it, and then ended up regretting it later. I think this happens a lot with younger devs and that's OK because that's how you learn. (Make sure they get assigned the mess cleanup when it doesn't work out though. LOL)

At hiring time, it can be very hard to tell the difference between "vanity/primadonna devs" and "devs who really like certain technologies which will possibly blind them". And even among the latter group, there are tradeoffs in hiring them. There are many reasonable places to set the dial on how much a hiring manager wants to take risks on that. But I maintain that, as with many other hiring criteria, erring on the side of caution is a reasonable choice. As I said, I think being excited about a cool language is a mixed signal.