It might be because most of the initial bloggers were developers or at least had fair bit of technical knowledge. They wanted more control of both, data and UI.

It might be because most of the initial bloggers were developers or at least had fair bit of technical knowledge. They wanted more control of both, data and UI. Personally, and I know several people who choose to self host various blogging softwares mainly because they didn't trust 3rd party with their data. Who knows if they will vanish overnight or hold your data hostage.