.. yes, for many of the reasons described in Spotify's microsite.
They have a monopoly, and they are unfairly favouring their own products.
This should be enough to bring anti-trust concerns to the table.
If you redefine "monopoly" to mean "minority market share," then yes, I suppose they do.
I have to imagine a fair number of Google searches for "spotify remove ads", too, which can lead to an upgrade.
I guess the crutch of Spotify's argument is that 30% is too high to charge while having their own competing app that isn't required to pay the same fees. Effectively using their unilateral control of the App Store and IAP to squeeze a third party competitor
Spotify can do this thing called "advertising". Look into it.
They advertise for Spotify Premium constantly on their free tier.