Because even Comcast, the most evil of the telecom companies, doesn't put out a web browser that seeks to permanently entrench its ad business. In fact, it lets me use any browser I want.
But, again, they don't seem to use Comcast Business Layer A to entrench Comcast Business Layer B. They could put a tax on every call to Stripe API if they wanted. They don't. The worst thing they've done is throttle Netflix (very bad) and the market spoke and they were shamed publicly.