While it’s true that Deathwing doesn’t benefit from allied abilities, I think you’ll find that he still relies on his team to be effective. We made a lot of design decisions to ensure that he doesn’t go too far in the direction of being completely self-reliant.
As one example, while he can’t be healed by allies, he very much designed around excelling during big teamfight engagements.
Because his abilities have such long wind-ups, he combos very well with his allies when it comes to receiving help in setting up a good Molten Flame, which can simply win engagements when done correctly. He also helps allied CC chains happen due to having fairly good follow-up CC, particularly when in Worldbreaker form.
When played optimally, I think Deathwing is absolutely at his best when fighting alongside his team. In 1v1 settings he isn’t nearly as potent due to his abilities being easily dodged due to their long wind-ups.
However, like many have said in this thread, you never know what’s going to happen until the hero’s released into the wild. What I will say though is that this was definitely considered during his design, and we’ve made a lot of changes over his development to ensure that he is still very much a team player.