1: both companies need each other. AEW will thrive as being seen as an alternative to WWE. WWE needs competition to actually spur them to create compelling content, and they could use a slightly smaller/less successful competitor to be able to compare their ratings/revenue to. If WWE is hitting 1.5mil viewers per show, it looks a lot better if the competition is doing 700k-1mil.
2: the illusion that AEW stays on WWE's dikk only exists because WWE is just being more subtle about their pettiness.
From a visibility standpoint, WWE wouldn't be able to throw their relationship with Evolve in the bushes, since it's pretty much already there. Then they just happen to decide to air their anniversary show on the same day as an AEW show.
They just happen to come up with reasons to pull talent from Starrcasts (which, despite being separate things, are closely tied to AEW events) after said talents have been used to sell tickets.
They sat on the Tom Magee match for ages, and then suddenly rush to get a doc aired on the network right before it was supposed to be shown for the first time publicly at Starrcast.
These aren't small coincidences by any means. They're all examples of corporate pettiness in action. So really, both sides should chill and let the other guys cook if we're gonna complain about it.
