The reason for cable shielding is twofold. First, it has to be sufficient to keep the RF from leaking out. Cable companies are required to monitor "leakage" because some of the frequencies they use are the same as those used over the air for such things as aircraft navigation and emergency communications services. Insufficiently shielded cable and poorly installed connectors allow the cable signal to radiate like an antenna and jam the over the air signals. Cable companies face stiff fines if they are found in violation of leakage levels.
Second, cable systems can be thought of as operating in duplex mode. Data is sent to you but it also has to send data back from you to them. Certainly, this can be understood for internet, but it also applies for TV and phone service. The cable boxes and modem constantly send data back to the cable company and this is why the same system integrity needed to prevent leakage is needed to prevent interference (called ingress) from entering the system and disrupting the return channels.
Cable companies have adopted their standard cable that they tested to meet leakage and ingress and that depends on the location of the system. Quiet locations can get away with an RG6 that has a foil shield covered with a 100% braid. That would be minimum. If you are in an RF noisy urban area and particularly those near transmitters you need to up the shielding to stop ingress, and quad shield may even be required. But I will agree that QS is overkill in most instances.
The good news is that fiber to the premises and Ethernet within the premises is replacing coax as streaming is becoming more and more popular.
-Hal