I seem to remember Dilbert explaining this as a way to ensure employees felt more like company-owned sacks of potatoes than actual humans. Hot-desking really does seem like one of the most dehumanizing office designs I can think of.
I know the supposed benefits of open offices, but I'm not even sure what hot-desking claims to achieve? Except in call centers I guess, where it's explicitly "to speed up firing people".
In call centers, there's another reason: if the company gets big enough, they may have more employees than desks. Since call centers work on shifts, not everyone is going to be in the office at the same time, and so they just lay down a policy of "nobody has their own desk".
It's mostly for environments in which the company's short on space and a lot of employees don't routinely come into the office. Hot desking eliminates permanently provisioning office space that may be only used for one day in five or ten.
If that's not the problem being solved, I'm not sure what is. Now no one knows where anyone is sitting and teams are at least theoretically all scattered around.
For permanent non-traveling roles, I don't immediately see the advantage though.