It's true but if you know which addresses have bitcoins, you can simply backup private keys of those addresses if you want. Surely it's more easily and even more safely to backup a wallet mnemonic seed words because it's easy to do such wallet backup and I don't see big reasons for don't do this and why a Bitcoin user must skip mnemonic seed words backup to use specific private key backups.
Since you already know that backing up private keys individually is less convenient and riskier (more prone to typos) than backing up the wallet seed, then I honestly don’t think it’s wise to suggest doing so, especially when we know that many newbies might read your post.
I wouldn’t suggest doing so, not only because it’s riskier and less convenient, but also because of you do that you give up one of the best features of hd wallets, which is enhancing privacy. A hd wallet generates a new address for each receiving transaction and also automatically sends change to a different address than the one you send from..