That is the thing, I play them regularly and I love multiplayer games like fighting, strategy, MOBAs, FPS games, etc. etc. In those I have almost no qualms or problems when loosing, but those are games where each match starts on equal terms.
In Hearthstone it feels like I have no real control of the situation. My randomly selected opponent draws random cards out of a random deck which all have random effects at times. If you have money you can probably edge your deck towards the winning side a bit by buying a couple hundred boosters, get the cards you need or be able to disenchant a few thousand cards you don't need to buy the specific cards you do want for that meta optimised deck.
It's not like a fighting game where you adapt your fighting style with a character depending on the opponents selection of a fighter, where you know "This character can do this and that, this is how I need to fight now to win". Here you are absolutely fucked if you haven't built your deck either with the most overpowered meta or don't have somehow extraordinary abilities of clairvoyance to know what you need to counter with your deck to have it ready before you click that search button. Unlike a fighting game I can't see what deck my opponent has selected, what cards he has, what I can do with my deck to counter his potentials, all I can do is play my cards and pray shit goes in my favour.
So you can tell me to "git gud" once I hear you "got gud" at a slot machine. Cause that is what playing this game feels like.