People are fooled by phishing emails all of the time. It is arrogant to suggest that anyone, including ourselves, are immune to falling prey to phishing. One of the reasons why so many phishing emails look like phishing emails is because the people creating them do not do due diligence when reaching out to their targets (e.g. ensuring that the email looks like it originates from a legitimate source). Another reason is that few of us are targeted directly (e.g. the phishers do not know whether we deal with the organization they are posing as). Yet the right combination of factors will leave anyone vulnerable.
If we can be fooled, shouldn't we expect the same of our filters? Sure, the filters may be better set up to identify certain forms of phishing and we may be in a better position to identify other types of phishing. Yet neither party is foolproof.
(Then there are things to consider like avoiding false positives, which will weaken the filters. It doesn't matter if those filters are automated or human.)