I don't know how it all works behind the scenes but my guess is that artists just dont want to be blamed for charging their fans a ton?

Ultimately if one ticketing company offers a band 200k to perform a night and another company offers 150k then every band is going to go with the 200k - even if there is a dynamic pricing model for the fans.

What is the "other company" in this example?

The last time I bought concert tickets it was through Vivid Seats. The last NFL game I went to was through StubHub.

Its my understanding that some NFL actually has an official deal to sell through Ticketmaster first - though presumably any of these other companies could have that deal if they paid the NFL more.

FWIW I do think ticket convenience fees should be eliminated (or made so they have to be listed upfront) and this would be good for transparency - but I am also pretty sure that doing so would ultimately just raise listed prices.

Some artists are large enough & successful enough that they don't need promoters.

Especially when the article itself notes that LiveNation often also represents the artists.