My ISP does not and if yours does, vote with your money or lobby your government to make this illegal.
And while at it, lobby to make corporate MiTM tools illegal as well.
Because if you are bothered about my little blog, you should be bothered that your employer can inspect all your HTTPS traffic.
Or you could do a much simpler thing and support HTTPS and not expect users to change ISPs (which is not always possible, e.g. in rural areas) or change laws (which is even less realistic) to browse your (or any other) blog. Injecting ads has nothing to do with corporate MITM, it's unquestionably bad, but unrelated here.
More to the point: serving your blog with HTTPS via Let's Encrypt does not in any way forbid you from also serving it with HTTP without "depending on third parties to publish content online". It would take away from the drama of the statement though, I suppose.
To add to that rouge ISP employees don’t care if it is illegal.
It's not just your ISP, it's anyone on the entire network path, and on most networks with average security that includes any device on your local network.