This makes sense to me. You should never rely on your CA to let you know that a certificate is due to expire soon, you should have your own monitoring in place that actively checks this for you.
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Yet it was still valuable to find those that fell through the cracks. At work, the emails prevented a couple of outages by expired cert, because a dev that left was renewing them by hand and we only found out when they left and the catch-all started to bubble them up to support.
Things fall through the cracks, or people are in a pinch and just forget to add the cert to the in-house monitoring system. The emails were a wonderful failsafe.
I wish I could just query LE to tell me all existing certain where the account is under my domain name. Extremely helpful to assemble a SBOM.