That's correct. The reference implementation of Bitcoin called "bitcoin core" doesn't support mnemonic algorithms so if you want to use your BIP39 mnemonic in it you'll have to derive the extended private key (xprv) from that seed phrase and then import that into core using "getdescriptorinfo" command with the desired derivation path.
Some people may hate me after I say this, but Bitcoin Core isn't a very newbie-friendly bitcoin wallet. BIP39 has been around for a decade, and they could have added support for it. The developers either don't want to, don't see a great need for it, or there aren't enough requests to add it. Sure, you can use the master private key instead, but it's even easier with a seed. Bitcoin Core's biggest plus is the full-node feature and being able to use a locally verified copy of the blockchain. Bitcoin Core as a wallet is of secondary importance and isn't for everyone.
Yeah, unfortunately core team hasn't focused on user friendliness as much as we'd like. There are still many things you can
only perform through the console by typing commands which is not user friendly at all.
Lack of support for a mnemonic algorithm is one of the missing features. As @BlackHatCoiner said they consider it safe enough although I don't agree with the reasoning (PBKDF2 being weak) regarding the quote below from SE I have to point out that Electrum also uses PBKDF2 with the same exact settings as BIP39 (2048 iterations with HMACSHA512), they defined their own algorithm before BIP39 and they use it because of the additional "features" it provides such as a version and a custom word-list not because BIP39 algorithm was weak security-wise.
Also, more generally, many Bitcoin Core contributors don't consider BIP 39 to be secure. It uses PBKDF2 which is generally regarded to be a fairly weak KDF so it isn't considered to be good for the secure storage of all of your Bitcoin. Some software (such as Electrum) used BIP 39 in the past but have switched to using their own mnemonic algorithm because of this weakness in BIP 39.