We've already seen that that's not true. Portland couldn't have kept Plumlee because of those deals, whereas they could have in the absence of them. It also prevented Portland from being serious players for Noel, because there's no way they could afford to extend him. Now, I do think Olshey made a good trade with Plumlee, but the idea that the space between the cap and luxury tax is "use it or lose it, so it's okay to completely waste it" is not true.
The "current market" is over. Analysts like Zach Lowe have been saying that teams over-leveraged (like, uh, one team we know) and are now scrambling to cut costs because they can't afford to sign their own impending free agents. The cap is barely going up, many fewer teams will have major cap space. Last season was unusual and created a bubble--contracts like Crabbe's, Turner's and Leonard's are the equivalent of stock in tech start-ups that were all hype. They're not going to suddenly start looking better with time.