Sure, for one site, that $3/mo will not break the bank.
But being limited to only $100/$3 = 33 sites a month would be quite constraining.
When I'm reading about a topic or searching for a purchase, I'll typically visit that many sites in one session. Over the course of a month it is normal to visit hundreds of sites (I have counted for auditing a job), sometimes over a thousand. That's without giving it any thought, just following links and reading linked content.
(Heck, when reading HN I sometimes read more than 33 HN stories in a single sitting, but to be fair I don't often follow the links to the articles themselves ;-)
If I had to monitor my usage to keep it down to 33 sites in a month, I could do that but it would be a very different reading experience than I currently have.
Like back in the days when we had to pay per minute of online access (outside the US, using audio modems). The change to a single monthly subscription with the freedom to read as much as you want, as long as you want, was liberating and transformative. It would be a little sad to go back to having to self-police reading in order to keep costs down.
