Winning the division and playing two NLDS home games would be more than worth it, and merely making the NLCS would be very worth it. And they are currently 4-0 against their likely NLDS opponent.
But seeing how timid they have been I'm with Taudawg, if all they have the ability to trade for is, "another Chase Anderson and Brandon Kintzler, except this time better," I'd rather sell. And that is doubly true when you see the Cubs and Nationals being so aggressive. The Phillies competitive window should have just been opening as the Nats' was closing, but when your team is all free agents you only get 3-4 years, not 5-7. And we never even competed, really.
People keep saying they'd rather focus on 2022 but clearly there are no deals to be made which will do that that don't involve a heavy prospect price. Even giving up Howard, for all his troubles, removes talent from next year's picture.
Dombrowski may have the rep for being bold, and as a short-termer, but he's also not completely dumb. He knows he doesn't have much to work with/can't afford to trade away too much future. At the very least, in March, he was probably expecting to be able to trade Haseley or Moniak or Kingery, or even for Bohm and Didi to be good enought to put Stott in play (since he's blocked until 2023).