Why buying a home is a common trigger
Life insurance needs tend to track financial obligations, and a mortgage is often the biggest one a household takes on. The Insurance Information Institute frames life insurance largely around situations where people depend on an individual's income. A new monthly housing payment is exactly the kind of obligation a surviving partner could be left to manage alone.
Whether you need additional coverage when you buy depends on your own circumstances: existing coverage, whether there's a co-borrower, and what savings you have. The point of this guide isn't to say you must buy something; it's to make sure you understand the options so you can decide what, if anything, fits.