Business sites rarely use comments, yet WordPress keeps the forms, menus and spam entry points open.
Why closing comments in settings is not enough
The Discussion setting only affects new posts. Old posts stay open, and bots post through feeds, the REST API and pingbacks.
Close everything at once
Forms, existing comments, feeds, REST endpoint and pingbacks, plus the Comments menu and dashboard widget.
Keep what you need
WooCommerce product reviews are comments too. Keep them on, they sell.
Do not delete, hide
Hidden comments can come back if you change your mind.
Disably does it in one setting. See the demo and other ways to reduce spam.
Frequently asked questions
Will disabling comments improve speed?
Slightly: fewer scripts and requests.
Can I keep comments on the blog only?
Yes, choose the content types.
Are product reviews affected?
No, they are kept.