A few things here. In my Quad Pidgeot deck, and I assume this is true for other Quad decks, is I always had a turn to just burn a Supporter, which was a Skull Grunt or a Team Rockets Handiwork. For me, even if I wasted a Skull Grunt, it
still gave me some information. My opponent doesn't have Energy or something to help them and I can plan my turns accordingly. That information alone is good, even more so if I have a Talonflame in the active spot. Banning Team Skull Grunt means Energy in a players hand is at least safe, given all the energy removal options that exist. Yes, the "luck" part is not knowing their hand but you get to see what they have. This is why Talonflame is so good in my Quad Pidgeot deck and why Sylveon-GX is good with these cards because you now know what you want to take out of the deck.
Crushing Hammer is another thing. I believe
@Otaku hates cards with coin flips because you never know how good they will be. I don't know if you played during the HGSS early BW days but there was a card called Pokemon Reversal, which has the effect of "post errata" Pokemon Catcher. The card was always bad, just like Energy Removal 2, which is Crushing Hammer now, except it never picked up but one day Magnaboar players decided to play Pokemon Reversal because of the decks ability to KO anything it wanted in one hit. A Worlds match happened (don't remember it completely) and one player in this mirror flipped all heads on their Reversals and the other flipped tails on theirs. This is the reason Pokemon Catcher (first version) was created and that was to make sure all players could guarantee their target but this was deemed too good and rather than banning the card, they just made it the "new" Pokemon Reversal, putting us where we once were and then placed the effect on a Supporter, which is still too good. After all this time, we proved once again as players that this effect is too good for the game and shouldn't exist, at least on a Trainer.
Crushing Hammer
could get this same treatment and get a version of it without the coin flip, which will break the game and with Turbo Dark still being a thing, this
could happen. I'm not saying these things can't exist because nothing (except win conditions) should be completely safe but the hand should be safer than the play field. For example, I feel my energy is
safer in play, where more threats to it exist, than they do in my hand because Team Skull Grunt exist. This is the reason Quad decks are so good because you can't manage your energy, a resource needed to win the game because they can still discard them with no real interaction