It has to join each part of the previous join to the next join, and if you have a lot of joins this can get out of hand.

We have a lot of joins in our final fct orders from our intermediate table, and looks like this:

from foo left join bar on bar.common_id = foo.common_id left join baz on baz.common_id = foo.common_id left join qux on qux.common_id = foo.common_id left join waldo on waldo.common_id = foo.common_id

So waldo joins to qux, which joins to qux... I call it a "staircase join", as that's what it looks like in the SF profiler.