Cable TV was first a means to get over the air stations to places where they couldn’t receive it. These stations always had ads
Next, cable started delivering the “Superstations” like the local Atlanta station TBS and Chicago’s WGN which had ads from day one.
The only channels that didn’t have ads from day one were the premium channels like HBO that still don’t have ads.
I'm signed into my TV and whenever friends cast a video Google mysteriously forgets that it's not allowed to show me ads.
That's because it's using their credentials when they cast, not yours.
That said, while I find those services pretty scummy for what they've done, I've fled back to spending a lot more time with books. There's plenty of them to read before I die and it's unlikely they'll be similarly molested.