Where core engineer really shines, imo, is supporting other players in a party for PVE, especially if paired with folks who aren't professional e-sports players. It condi cleans and burst heals insanely well, is able to take down almost any break bar alone, stacks might and aoe revives, all while having access to a 12 second stealth without any trait or skill swapping. I don't think there's any other class that can beat engineer at being a support hybrid, I still sometimes come up with new tricks, even after playing the same build for 4 years. As a DPS class, it's very complicated for the mediocre damage it deals when compared to the rest, and you'll also lack most of the party benefits that a support core engi brings in. But the same goes for healing, another heal class does it very easily compared to an engineer and can keep the whole crew topped up most of the time, but they won't have as many tools to handle a tougher situation... like having to stealth and revive 3 downed players stacked with a bunch of bleed and burning, so you can get the aggro from the boss so he doesn't maul your buddies to death with his next attack... Or having to burst heal someone at maximum mortar range.