I just read up on the way cards are acquired in Runeterra, and I can say with some confidence that the game is utterly doomed.
By limiting the number of cards you can create with a weekly cap, they are essentially saying the people who have been playing the longest and logging in every day are automatically going to have the biggest collections.
That may seem great at first -- keeps things from being all "pay to win" as the kids like to say these days.
However, think down the road a bit. This model is going to be a huge turn-off for new players. No one is going to want to pick up a new game if there is literally no way to catch up with veterans. People complain about it enough in Hearthstone, saying it's a crime that you have to pay money to be able to compete. Well, in Runeterra, you literally cannot compete at all until you've put in your time!
Maybe I'm mistaken about how all of this works, or maybe I missed a piece of the puzzle. But as I understand the system now, it's terrible and the game will never have whales, meaning it will never make any money.
If publishers would stop all the pretense of "free to play" and just admit that games actually cost money -- that they need to have a cost in order to survive -- we could move to a model where people just pay one set price and get all the cards. We need to set aside this collectible model as a relic of gaming history. It kind of made sense for physical cards, but it will never make sense for digital ones.
I think the new player experience argument is a very strong one, but the problem you're talking about is way too far down the road to think that it's a death knell of the game. And I think you're ignoring the other side of the problem - the F2P slog most of these games feature, and the sense of sunk cost that comes with leaving your old digital card game(s).
Getting a full collection is generally impossible for F2P players in HS, MTGA, etc., because each game includes over 1000 cards (not counting duplicates) and new sets are released regularly. Fun meme decks and meta decks alike tend to require expensive, build-around cards, so F2P players tend to spend a lot of time getting to that one deck. At the point that you've built one or two good decks, you're hugely invested. That investment of time (and money for non-F2P) is a powerful way games like HS hold on to their player base in spite of good alternatives - no one wants to switch and have to do it all over again.
This is the problem their system claims to solve. Even after accounting for duplicate cards, Runeterra will have fewer than 1000 cards, so it's far more approachable from the start, and this "better F2P" model is Riot's way of telling players it's safe to switch - you won't have to grind to be competitive, people won't be buying meta decks and beating you at the bottom of the ladder, etc.
I don't know how Runeterra will solve the new player experience after a couple of expansions, but that seems solveable. Maybe Runeterra will limit the number of cards in standard more strictly than other games, or relax the constraints on buying wildcards as they add more cards to make it easier to catch up. Either way, their biggest problem on day one is going to be convincing the millions of HS and MTGA players to switch.
Before signing off, I also want to quickly address the point you bring up about the absurdity of F2P. The devs have said that there will be cosmetic content for sale (e.g. customizing card backs and your pet, maybe those emote stickers), and there is a gate-limited way to buy wildcards on a weekly basis. I think that's actually a pretty good strategy for monetizing - by making the only game-relevant content for sale wildcards, I think they'll actually be able to convince traditionally F2P players to spend a little bit to get exactly the cards they're after (rather than a bunch of random packs), and selling cosmetics works well for a lot of games without compromising the content of the game.