I think it's tough with card games because they come from a physical form of lootboxes. Being expensive is kind of baked into their lineage. Collecting cards is a big part of the fun, and if you made it very easy to do I think it's hard to say whether people would enjoy them as much.
I don't play any collectible card games anymore because I don't want to pay for it anymore, but there is something very entertaining about the model even if it's easy to argue it's a scummy business model by today's standards.
I haven't looked into this game beyond your description, but it does sound like a pretty weird model. Do you also have to pay for cards on top of that?
I remember kind of disliking the arena system in hearthstone because I liked the game mode a lot, but as a casual player it was really hard to get to play it much. I guess they wanted to keep people from spending all their time there since you didn't need to buy cards to play. I much preferred magic arena's drafts where you pay an upfront cost but get to keep all the cards you played with. Much more accessible for casual players and more satisfying, too, since you always get something out of it.
Oh I see. Sorry for the off-topic response then!
It's a shame that multiplayer games really struggle with paid models these days. It heavily cut into a player base if things aren't free to play. That kind of forces all but the biggest releases to turn to other monetization models in order to keep the base game free.