No, because you still had the expansion draft to deal with unlike before. The point was that teams were unlikely going to be able to cover all their issues with 1 trade unless that trade was with Vegas.
Whoosh. The point was that's a laughable threat for Vegas to make since it was the status quo before their existence.
Vegas: "If you don't deal with us then we won't deal with you!"
Team A: "Uh, ok. What about the other 29 teams we can and have been dealing with?"
Vegas: "..."
To your second point, there were teams that could've greatly improved their situation with one trade. Even for the teams that couldn't, there was plenty of time to make more than one trade. There was a whole year to wheel and deal from the moment the expansion was announced to the moment the draft took place. What's more, the expansion wasn't a secret. Teams would've known about it well ahead of time - they had to agree to it, after all.
And I get your point about it being easier to just deal directly with Vegas. I'm not disputing the convenience factor. The point was that Vegas benefitted because teams didn't find alternative means to deal with their problems.
The teams learned though. GM's (especially ours at the time) are known to be far more reactive than proactive. Didn't see too many deals go down with Seattle.