But we might disagree on how players are kept engaged. For me the objective is to encourage users to buy new cards. A way of doing this would be by designing a system that sets up games with a back and forth, whereby if you lose to the same superior counterplay cards you would need to get cards to counteract the patterns you are being shown. Thereby boosting sales.
That's a double-edged sword, though. I understand wanting to motivate players to buy new cards, but it can just as easily backfire and demotivate them to continue. It's already bad enough that some players get annoyed just by facing certain factions/decks (over and over again). Hard counters are even more painful.