The first decade was non-free with later various shades of semi-free. Around the turn of the century it was apparent Gnome was going to dominate the market unless they acted quickly, so they GPLed at that time to maintain relevance. They're still around; guess that strategy worked.
Having lived thru it, the situation was much worse than you imply. Its not that the non-free licenses didn't allow closed source or whatever, they more or less intentionally carefully prevented distros from legally including Qt. Just barely tight enough that on technicalities it failed the DFSG, intentionally. Debian couldn't include Qt and therefore KDE in main until the 2000 relicense.
Having lived thru it, the situation was much worse than you imply. Its not that the non-free licenses didn't allow closed source or whatever, they more or less intentionally carefully prevented distros from legally including Qt. Just barely tight enough that on technicalities it failed the DFSG, intentionally. Debian couldn't include Qt and therefore KDE in main until the 2000 relicense.