This old post from 7 years ago said what I feel about streaming even before I was saying it.
https://www.part15.org/community/temp/i-just-do-not-get-it-internet-radio-versus-fm-radio/
Well, it's like everything else. Depends on what you want to do.
There are certainly downsides to streaming. While the potential is there to get as many listeners (around the entire world) as your internet connection can handle, the reality is that there are hundreds of thousands, if not millions (particularly if you count podcasts) of them out there, and the chances of being found accidently are pretty remote.
Even if you advertise, there are so many advertisements bombarding people all the time that you're likely going to be ignored.
Now, since there are limited numbers of FM channels, there is naturally more of a chance for someone tuning around the band to find you. But that would be in a severely limited geographic area, particularly in the U.S. where Part 15 rules reign (as opposed to Canada's BETS). I suspect the chances of accidently getting listeners that way are pretty remote as well.
However, streaming can be useful. You know that your stream exists, and it can extend the listening area for you. If you advertise its existence locally, not on Facebooks and similar sites, but in person, or with flyers, it can also extend the local listening area.
Of course, the same holds true for FM, making the entire argument, at least to me, a wash.
If you want listeners other than yourself, you have to give them reasons to listen. Those reasons would vary, depending on your location and the makeup of its potential audience. And then you have to let them know that you're there.
Some of the reasons could include being ultra local, or really focusing in on a segment of the listeners, such as seniors. Again, depending on location, and what you want to do.
It can be helpful to analyze and think about the psychology of 'wanting listeners'.
What is going on inside our emotional brain when we 'want listeners'?
I would say that our primitive brain as a social animal has a natural desire to be noticed and admired. Other traces of it can be noticed in relationships with parents. For example we want daddy to appreciate the fact that we can 'play catch with a ball'. A good father will voice his praise when you catch and pitch the ball. In that situation I would be a bad parent because I would be greatly bored and disappointed by children who wanted me to waste time on sports. I would be much happier if a child of mine took great pride that I had one of the best part 15 radio stations of any dad in the country. The brat would listen to my station and know how smart it was for me to carry the 'Jazz Fest'.
Carl in his usual humour brought up some good analysis of the human desire to be noticed. We want to be noticed for accomplishments. I used to play the guitar. I used to compose my own songs. I don't now and quit a long time ago...why....because I never picked it up, learned, practiced, to entertain flies on the wall. If I compose what I thought was a great song if I can't play it for others to be appreciated for something I accomplished what's the point? I want listeners! I did it to play in a band and for an audience, not for entertaining the walls for "my own enjoyment" This can apply to lots of things.
Like my station, I want listeners. There's a certain pleasure obtained from getting others to notice something I accomplished. We do our stations, it takes know how that all can't and most don't do. Processing, programming, automated broadcast programs, scheduling shows,
transmitting it to the public with an expensive transmitter and processor to sound like the "pros" is done for more than for ourselves. Same as the guitar comparison. Does an artist paint pictures to be the only one looking at them? Does someone write a book to be the only reader? You get the point. Also the listeners with over the air may not be known to you so there's the unknown/mystery that your transmission is getting to someone which gives the feeling of satisfaction of an audience. You are broadcasting to the public, you never know your true audience.