Yes, there are all sorts of reasons to doubt Dubas' ability to ever build a Stanley Cup winning team. It's okay to acknowledge them. He's made tons (tons) of mistakes.
On that note, examining his trade history:
Good:
Karlsson for Norris, Tierney, DeMelo, Balcers, 1st (Stutzle), 2nd (Rees), 2nd (Ostapchuk)
Pageau for 1st, 2nd (Greig, Kleven)
Dzingel for Duclair, two 2nds (later traded)
Brassard for Gustavsson, 1st (JBD)
Dadonov for Holden, 3rd (E.Pettersson)
Cap space for Coburn, Paquette, 2nd (Nordberg)
Lazar for 2nd (Formenton)
5th (Drozg) for Condon
Bad
Zibanejad, 2nd (Berggren) for Brassard
Stone for Brannstrom, 2nd (Sokolov)
Turris, Bowers, 1st (Byram) for Duchene
Duchene for Abramov, Davidsson, 1st (Thomson)
Hoffman for Boedker
Gustavsson for Talbot
1st (Korchinski) + 2nd (Ludwinski) + 3rd for DeBrincat
Paul for Joseph + 4th
Dahlen for Burrows
2nd for Murray
2nd for Stepan
Obviously made a larger number of deals than this, but I just looked at the trades that were consequential and were either clearly good or bad moves.
Made some good trades but overall he's made more bad deals and importantly the bad deals have been far bigger and more consequential than most of the good deals.
That, combined with his horrible cap management (which I pointed out earlier in this thread), objectively makes him a bottom tier GM.
I don't know how you can look at his history of trades (and overall acquisitions for that matter) and come to the conclusion that Dorion has done a good enough job overall to remain in his role, but I expect the usual suspects will find a way to convince themselves of it, regardless of the facts.