Outside of the Nexus of Fate win, the big problem with Darksteel Reactor in Historic is that it's basically a version of Simic Ascendancy that's harder to win with
While it's unlikely that every one of your opponents will be hit hard by this ability, it's fair to say that at least one or two will find it a nuisance
Many of the players who participated in the system are bowing out of the game, looking for their next career move
Mulligan hard (put back cards to draw more) for them, trying to keep a turn 1 and 2 character if you have them already
You can use the cards you throw out this way to fuel Zemos boast effect, which lets you bring three of the cards that you chucked into your graveyard straight back into play without needing to pay their costs
Maybe youre not completely sure whether or not your work needs, well, work