From what I've heard, GTK was born due to licensing restrictions of the older versions of Qt - Qt used to be dual-licensed, available either under a commercial license, or under GPL (not LGPL). Some people found that too restrictive.
No. Some people (especially the FSF) objected initially to the FreeQt license (which did not meet OSI and FSF definitions) and then the QPL[0] for a few reasons, most importantly because it was not GPL-compatible.
Qt/X11's release under the GPL came quite a bit later after GTK+ and GNOME were well on their way to becoming established projects.
