You've done a strong job of describing what I felt years and years ago, and have come to learn is the lay of the land still in the music business. Labels have done a fantastic job of maintaining their gate-keeper status and of being able to break new artists into the mainstream. What didn't change with the internet is, partially kidding here, that 14 year old girls decide what's going to be popular. Outside of that, it's pretty much table scraps.

But...there are some exceptions!

There are certainly a handful of examples of responding to the last question you pose - re: being independent and achieving mainstream success. The ones that I find the most relevant are CHVRCHES (unsigned, SoundCloud got them attention, eventually had their pick of labels) and Macklemore (independent, used major label distribution services though). Also Skrillex - his label had no interest in his bleep-blonk-screech-BASS DROP tunes and he set it free online and got that avenue going - now he's got his own label and millions in the bank. There are some outlier musicians like Prince who are genuinely contentious with both industry and fan expectations.

I think more and more artists who grow up as 'one-person operations' (think Grimes) will navigate a new business platform. Labels will specialize in these artists, or management teams. Eventually though, there does exist a plateau where it seems inevitable to have to deal with a large entity such as LiveNation or Ticketmaster...neither of which are very well regarded as customer friendly in this day and age - at least not as much as direct-to-fan opportunities. The next 10 years should be interesting both in the US and globally.

Oh, and in my opinion, artists tend to start labels as a compensation mechanism to get more power for their own business enterprise, and potentially profit from the success of others signed (see: Cash Money / Young Money Records).