That advice is using an investment account with a security (called ‘house’). By updating the fake security ‘price’ you update the asset value. This treats a house like a purchase of shares. It’s a trick, but it works. This way you do not have to record the unrealised gain(s) against a category.
Using an asset account you simply add a txn for the increase, but the gain has to go against a category.
Because of the complexity of my investments, I created a separate base-level account set to keep detailed track of them, with the various types of accounts (taxable, tax-deferred, and tax-free) within that investment account set. In my current account set, I have an asset account corresponding to each of the accounts in the base-level investment account. (Note: in the investment account set, I have asset accounts corresponding to each account in the current account set that may be a source or target for transfers. However, the value is not kept current. Reliable asset values are only on in the current account set.)
Weekly, I record the net change in value of each investment account in the appropriate asset account in the current account set, assigning the number to an 'Asset Changes'.
So, at any time, I can quickly check my net worth via the current account set.