they no longer need to implement such policy coz they already have the ability to block/filter a certain user to connect to a certain vpn server without having to register to any of their products or don't have enough credits to access over their connections. And besides those third party VPN servers plays a role to lessen the burden of their systems when it get bottleneck by a millions of subscribers accessing their server at once by giving the user the freedom to choose which server he is going to use by just using vpn. its not a fact but logically it make sense. Now it only depends on how the user will going to use VPN. at my point of view the reason why this big 3 isp provider also offers VPN services is simply to reduce the access to their main server by rerouting a certain user to a diffrent server through VPN and can also make money at the same time.
dili ko swito hap..
plz enlighten me mga guru diha.