I've just tested the -silent parameter; everything functions as expected now.
I'd consider this solved; the only thing I'd request is -silent having a graphical configuration option to expose this functionality to all users.
Per the last comment, closing as fixed some time ago.
@Myrddin-Wyllt, always starting Steam with no UI visible sounds like it will cause more trouble than the value it would add to the Steam client. If you want to do this, manually create a desktop shortcut that calls steam -silent.
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window "connect to account" not show, it's normal
library not show, normal too
but latest chat dialog and friends list opened