I'm not a fan either, even though I have never used a critical hit deck or chart (and I don't intend to). It feels to me like overindulgence in making random tables, and this is coming from someone who uses a ton of random encounter tables in his campaigns.
I personally feel that critical hits and fumbles, should have some relevance to what is happening during the session. I don't want a weapon to break or drop from a player's hands, just because a card says so. I fear that these systems tend to lean a lot towards these sorts of odd and disastrous outcomes. I don't want to be overly punishing when my players roll fumbles, or overly rewarding when they crit. This isn't Zelda - Breath of the Wild (weapons don't break every few seconds and are competently made) and the pc's are competent heroes who don't just drop their weapons mid-battle, unless there is a very believable reason. Most importantly, I don't want there to be a disconnect between what is happening in combat, and what I narrate as an outcome of a crit or fumble.
An excellent example of the sort of fumble-narration that I aim for, occurred at the start of my pirate campaign. A player was trying to sneak up on a cannibal in a watch tower, but upon attacking the cannibal, he fumbled. I ruled that just as he was about to swing at the cannibal, the cannibal heard a small creak of the wood, and in a reflex was able to grab his wrist to stop him from swinging his sword. I then had the cannibal make a free grapple check, and the two became locked in a desperate struggle on top of the watch tower. The cannibal tried to push him over the edge of the tower, while trying to knock the blade out of his hands. Because he was now locked in a grapple with his foe, he was unable to swing his sword. The player decided to drop the weapon himself, so he could draw a small dagger instead. This felt like a much more believable outcome, although it still ended with the player's weapon dropping to the jungle-floor below.
It became a very cinematic fight, because I didn't let a random table decide what the result of his fumble would be. Instead of punishing the player by snapping his sword in two, or having him (a competent warrior) drop the sword for no good reason, I rewarded him with an exciting scene instead. I don't think a crit/fumble deck can do that, and in fact I think it steers the DM away from narrating the dice results in the way that I prefer.