Example of a question where this tag would come in handy: How expensive is it to play bassoon in high school?
We don't need this tag.
First of all, the question you linked asks what the cost of maintenance is for a bassoon. While this information is to be used for choosing an instrument, the question is not directly asking about choosing an instrument. The tag
Bassoon is fine for this question.
The site does not include shopping advice or recommendations. While the example you gave is not shopping, the tag will mostly be used for these types of questions. They are naturally subjective and cannot be directly answered. This is why we avoid them.
There is also a close reason which reads:
"Questions seeking recommendations for specific equipment are off-topic, because they are primarily opinion based. Instead, describe the required function and setting in which the equipment will be used, and ask what you should look for to achieve that."
Instrument-choice sounds a lot like "recommendations for specific equipment" to me.