Guest checkout
Guest checkout is a checkout that completes with a delivery address and an email address, without the shopper creating an account, choosing a password or confirming anything from an inbox first.
For a human, forced account creation is friction. For an agent it is usually a wall, because the account flow adds steps that live outside the storefront: an email to open, a link to follow, sometimes a code to read back. An agent acting for a shopper generally cannot do that, and the ones that can are the minority.
The commercial argument for accounts is real and this is not an argument against them. It is an argument against making one mandatory before the order can be placed.
Why it matters to a store
This is one of the few checkout fixes that is a settings change rather than development work on most platforms, and it converts a hard stop into a completed sale.