I am not sure how much article is misrepresenting the seriousness. I travel air Canada 30+ times a year. GTE strictly means what it says - you don't have seat assigned and you may get one at the gate. They cannot help you at the checkin until they know who all is boarding. So from that perspective strictly, I understand that sending them to gate to await their destiny,rather than try to resolve at the checkin counter…
There’s a world of difference between “your seat will be assigned at the gate” and “your seat may be....” The former, which is what I think most airlines actually say, strongly implies that you do have a seat, though they are still determining which one it is. The latter is often what they really mean.
If you are reasonably savvy, the fact that this is unusual ought to clue you in. However, that signal now is a bit diluted with all of the games airlines play to get you to pay extra to choose a seat so....