The better comparison in my mind is with Golden State and Harrison Barnes. Golden State was not going to max out Barnes, when they also had Curry, Thompson, and Green. Dallas knew this and gave Barnes a max contract, that they would later regret doing. Don’t get me wrong, I like Jaylen, but his level of playmaking skill is closer to Barnes, and nowhere near the level of Harden at this same point in their careers. Elite playmakers are those rare max type players that are deserving of the contract, whereas 3&D guys are simply not.
They let Barnes go to sign Durant.
I'm not certain Golden State knew they could get Durant, when they didn't match the offer from Dallas. I thought KD had his sit down with Golden State a few days after the start of free agency. However, I thought Dallas offered Barnes the max on day one of free agency, which started his clock for Golden State to match. If I recall, Golden State hadn't even met with KD during that matching time period. They were willing to let him walk because they knew he wasn't worth the money.
This is not how things worked. I don’t remember when Barnes came to an agreement with Dallas, but they wouldn’t have actually been able to sign an offer sheet, thus “starting the clock” until I think July 11th that year (maybe July 8th) after the moratorium ended. Durant announced he was signing with Golden State on July 4th (that I’m positive about), and Golden State rescinded their QO to Barnes in response, so Dallas could sign him outright, no offer sheet necessary.
EDIT: The moratorium ended July 7th that year (was originally July 11th), but that was still after Durant had announced his intention to sign with Golden State.
Back when I wrote this thread I considered using the Barnes situation instead of Harden but because of the Durant factor I did not think the comparison is as clean as the OKC Harden. GS already knew they had his replacement and might have tried to keep Barnes since he was an original member of the 'death lineup'. They at least knew Barnes would have been a fit long term.
A big difference IMO is that despite getting paid by Dallas, Barnes did not really have the star potential that I could see a team like Atlanta thinking that Jaylen might. Barnes was at the time viewed as a contributor on an elite team but there wasn't really the lofty All Star expectations that I believe Jaylen may garner.
GS probably knew that letting Barnes walk wasn't going to hurt them too bad in the long term. Presti seemingly underestimated how badly losing Harden would end up hurting them and it's possible that DA could get similarly burned by letting Jaylen walk.