I only said an additional guest WC. Most houses have 2 bathrooms as standard anyway, that is clear. But an additional guest WC may not always be necessary.
In fact, most houses do not have 2 bathrooms as standard. Nowadays, bathrooms are usually built in the attic. Occasionally, you will find a children's bathroom as well. So 2 fully equipped bathrooms are definitely not standard.
Standard is:
1 fully equipped bathroom in the attic 1 guest WC without shower etc. (only toilet + washbasin) on the ground floor