> the goal of ideas like these is to reduce income disparity

Except when they're not. That's the point of this article. UBI is one of those ideas that can be all things to all people depending on the details.

For example, say you set it at a level that could sustain an able-bodied person temporarily but needed supplementing for comfort. Say you then remove all other state funded payments. That's UBI.

For example, say you set it at a level meant that most people could comfortably live off it and was topped up where necessary e.g. disability payments. That's UBI.

Of these, the first is, arguably, purer UBI. It'll also do very little to reduce income disparity.