Why Core does not support the "spawn a wallet with 12 words" format?

For instance in Electrum when you create a wallet you can spawn your wallet anywhere on the planet by remembering 12 words. This is insanely useful. With Core you have to carry a wallet.dat, and then encrypt this file and try to hide it somewhere safe. You can't cross borders with encrypted data since they stop you on customs check, airports, etc. If you upload the wallet.dat online even if temporarily and encrypted it is a risk because it got saved on some HDD server.

Anyway my point is, why you can't do this in Core exactly?

What i've found related to this is this:

https://bitcoin.stackexchange.com/questions/88237/is-there-a-reason-to-why-bitcoin-core-does-not-implement-bip39

Andrew Chow explained how BIP39 isn't considered secure and that is why Core does not implement it. But then he also explains Electrum does not use this anymore, yet Electrum still gives you the option to spawn wallets with 12 words. On the Electrum website they say: "Electrum 2.0 derives keys and addresses from a hash of the UTF8 normalized seed phrase with no dependency on a fixed wordlist.". So the question would be, why isn't Core using this method for wallets then? Electrum devs still consider secure the "show 12 words for seed" method when creating wallet, why not Core?