There are plenty of reasons... the first being if we trade Rudy under the assumption we are building around Donovan versus rebuilding then what we look for in trades is going to be very different. Same thing with Conley and Bogey trades. You also build with constraints of trying to please a guy who likely is going to leave anyway.
If they do deals that simultaneously please Donovan while also aiding a rebuild then go ahead and give it a go and I won't be too upset... I prefer to get the tank started early but as
@KqWIN has mentioned you can always tank. For example the Washington Conley deal that gets us KCP and Deni... that works under either scenario imo.
The Atlanta deal could become a bad deal if we don't pick up some firsts... in all reality it would include Capela and Collins... both have contracts that could throw a kink in your plans if you rebuild or if they struggle with injuries.
The most important thing is getting a good return when you move those pieces imo... and if the return is good right now on Donovan/Rudy I move them both. IF the return is meh then sure "build around Donovan" but only do deals you would do regardless of if Donovan likes them.