While small sites with a handful of staff, can't do that. People may subscribe for big sites like Facebook and Youtube , but they won't subscribe separately for a lots of small sites.
So blocking ads helps eliminating the small guys while the whales can deal with it.
Not true, they also help the end users, who often get lost in these discussions of big-vs-small companies. Turns out these "whales" everyone is so anxious to target provide benefits to end users, who are often the ones that end up bearing the brunt of the pain.