They literally sell out concerts.
They have a huge internet fan base.
They have millions of streams on Spotify
Let's look at Squid then under these metrics.
They sell out concerts? Possibly. Their last show in Philadelphia (albeit in 2021) was at Johnny Brenda's. Capacity? 250. Although that's a step up from their previous Philly stop at Kung Fu Necktie- Capacity 140. In their defense, their upcoming show in February is at Union Transfer, which can hold up to 1,200. But let's see how ticket sales go.
Squid also currently has 187,465 monthly listeners on Spotify. For some comparison to charting Alt artists:
Noah Kahan- 15+ Million
Nothing But Thieves- 5.1+ Million
Little Image- 284,000+
Bad Omens- 4.4+ Million
How about some non-charting Alt artists?
Teenage Wrist- 295,000+
Ruston Kelly- 630,000+
A completely unsigned band from West Virginia that I follow, called A Story Told, has 178,000+ monthly listeners. Based on your metrics, this band who doesn't tour and just makes cool music on the side deserves to be regularly played on Alt radio? Their songs have millions of listens too.
As for having a "huge internet fan base," that's completely subjective.
We get it from your multiple odd posts... the music you like isn't fully represented on Alternative radio, and that sucks. But radio is a business first and foremost, and the Alternative music format is fractured like never before with sub-genres that some parts of the demographic love, and some hate.
You also stated:
alternative is supposed to be a format that breaks artists that are underground,
Nope. Again. Alternative is supposed to be a format that targets a certain demographic to make money off of. Just like Country. Just like CHR etc.
Anyway, that's all the time I have for you. If you'd like to prove everyone wrong, there are plenty of radio stations up for sale that you could try your version of Alternative on. Good luck.