Why can't they let you buy/trade from the app? I don't know a ton about crypto as I haven't been following it for the past several months, but it seems it would be a million times easier and more convenient.
As far as my understanding goes there is going to be a way to onboard easier as they realize it's a barrier to usage, but like all development requires a lot of work and is in the pipeline.
Having their own blockchain could mean a lack of security/decentralization. Malicious actors can try 51% attack (if it’s proof of work)
It's Proof of Stake based so that wouldn't apply as it wouldn't be profitable or practical.