But that telco doesn’t get a cut with every other digital asset you buy using that phone you purchased from them.
Are you speaking of how smart and feature phones before the iPhone were carrier-locked in certain locales, and could only install applications which were approved by the carrier through the carrier's store, and the cost of the app/ringtone would show up as an additional charge on your monthly bill?
The reason carriers stopped restricting and charging for digital assets is the iPhone. Apple negotiated an exclusive carrier deal with Cingular/AT&T, who was desperate, and got every term they wanted including full control of the App Store with no profit sharing. They justified this by saying that there would be no carrier subsidies. A few years later, not only was Cingular willing to subsidize the iPhone, but the other carriers were also desperate and took those same terms.
They simply weren't able to capitalize on the position the way Apple was, and they realized they made far more by charging for newer high capacity data plans than they ever did on ringtones.
Telcos can't really charge for the contents of the data, any more than Apple attempts to charge web pages rendered by Safari. That is because they don't have a contract saying that the data provider or website host will pay them for certain services - the way Apple has with every single active App Store developer.
FWIW, today the telco and cable network tolls are usually the subject of network neutrality - such as perhaps throttling data into their network from streaming media providers until they are willing to sign comprehensive 'colocation agreements'. People do make a similar case that Apple doesn't invest as much as they should into Safari development because any lacking features will push people toward native app development.
Apple is taking ongoing revenue from every possible digital asset in perpetuity after the sale of the major asset has been done in the form of a tax that only impedes the digital businesses that actually created the novel valie.
You are replying to a post of mine where I listed the exact conditions and also a list of exemptions. That's even ignoring the presence of Safari, which among other things are used to provide hosted media as well as subscription, cloud-hosted gaming platforms.
I don't know what "every possible digital asset in perpetuity" could be speaking to.