This misses the problem explained in the article, which is that there are scenarios where events are "acked" but things still go wrong because of bugs.
For example, you rolled out code on the receiver side that did the wrong thing with each message. Now there's no way to replay the old webhooks events in order to reinstate the right behaviour; there's no way to ask the producer to send them again.
The only way around this is to store a record of every received message on the receiver side, too, which the article author thinks is an unnecessary burden compared to polling.
Personally, I think push is an antipattern in situations where data needs to be kept in sync. The state about where the consumer is in the stream should be kept at the consumer side precisely so it can go back and forth.
For example, you rolled out code on the receiver side that did the wrong thing with each message. Now there's no way to replay the old webhooks events in order to reinstate the right behaviour; there's no way to ask the producer to send them again.
The only way around this is to store a record of every received message on the receiver side, too, which the article author thinks is an unnecessary burden compared to polling.
Personally, I think push is an antipattern in situations where data needs to be kept in sync. The state about where the consumer is in the stream should be kept at the consumer side precisely so it can go back and forth.