If you eat a buffet and only have one plate, you don't get to complain and ask for a refund.
> keep charging them until they notice months or years later is indeed exploitative.
When is it the customer's fault for not cancelling? You're working very hard to avoid responsibility for the business contract you entered into.
> they stop experiencing marginal costs for me.
Which are a small part of the overall cost structure. So what?
> Nobody went out and bought another server just because I signed up
Absolutely they do. The business is managing its finances under the assumption of subscribers and LTV, and making investments accordingly based on those assumptions and forecasts.
> they're just exploiting me
For charging you for something you signed up for but were too lazy to manage properly?
> just get my money in without regard for whether I was going to get anything out of it
There you go passing the buck again. It's your responsibility to use the thing you signed up for.
> People who take money without providing value are at best economic parasites
You mean the money you're giving them as part of consensual business agreement?