Microphones do matter
In this recent article, I argued that, for most purposes, it doesn't matter that much which microphone you use.
But there are times when choosing the right microphone really does make a difference.
Vocals, for instance, are very sensitive to microphone selection.
Of course, the first rule of getting good a good vocal recording is to get a good singer. Don't like the sound? Then get a better singer.
But there are occasions where it isn't feasible to replace the singer. One is when the singer (or band) is paying for your services. Another is when you want to record yourself!
While any microphone of a decent professional quality will be able to capture a vocal that is clean and clear, sometimes you want just a little more.
To get the type of vocal sound that is popular these days, it is necessary to place the microphone quite close to the mouth. Microphones tend to be less accurate when used very close to the sound source. The frequency response will be altered by the proximity effect. There may be some distortion. And since the sound field is strongly curved close-up, the microphone may react differently than it would if used at a typical listening distance.
So, as any experienced engineer knows, to get the best out of a singer it is an extremely useful exercise to try out a selection of mics and see which works best. And for any one singer, the best mic for their voice might even change from day to day.
Another occasion where selection of microphone is important is when you are trying to reproduce a particular sound.
Suppose for instance that the client liked the sound of a certain recording from the past, and you know that it was probably made using a ribbon microphone, then you really have to use a ribbon microphone to get the same sound. Nothing else sounds quite the same.
And if you want to achieve the characteristic sound of a vacuum tube microphone, then you need a vacuum tube microphone.
So in summary, although for most purposes the differences between microphones are much less significant than differences in microphone positioning, there are times when you need to find exactly the right mic for the job.