No way to reasonably earn packs/cards from previous sets.
This is not a new problem, but has become painfully visible now that LOR is the newest available set, and it is not standard-legal.
There are just not enough ways for a player to start building their standard collection right now. Jump in was great for this, but now it only has non-standard legal cards.
The bigger issue here is that MTGA seems to go all-in on their most recent set, and really leave previous sets in the dust, which makes some sense, sure - but there are TONS of cards that are still very playable in standard that are basically unavailable to many players due to how the economy works.
Packs just are not cost-effective, and feel terrible to pursue, since it's just gambling with extra steps. Drafting is locked to the most recent set, or left on a single slow rotation through only one other set at a time (QD). Drafting is also abysmally difficult to get into as a new player due to the cost, as well as the odds that you'll get essentially no rewards because of the learning curve.
This probably isn't an oversight, I'm sure - but there are so many ways to get cards in the game, it's a pity nearly all of the ones that are worth my time/money are from only the most recent set.
Please at the very least bring back Jump In with standard cards.