10% is a lot but given that we are talking about extra money, it wouldn't impact me. If I stopped blogging, the blogs would progressively earn less and less for sure, but the majority of the income comes from posts that are from several months to several years old. So no, they wouldn't lose 10% revenue per month.
The gist of what I'm saying is that the majority of the revenue (which we may define as the baseline) is, for all intents and purposes, passive income akin to having self-published an ebook or an app in the past.
Besides, even if we disagree on the definition, the original question was about "small/passive" income. The OP clearly wanted to know about extra income on the side, more than limiting the field to 100%, strictly passive income sources.