I think this is something of a storm in a teacup.
On the main https://www.uscis.gov/visabulletininfo page, someone has forgotten to update the Current Month’s Adjustment of Status Filing Charts wording for EB to reflect the fact that Filing Dates can be used.
The actual USCIS page for October 2018 still shows that Filing Dates can be used.Current Month’s Adjustment of Status Filing Charts
For Family-Sponsored Filings:
You must use the Dates for Filing chart in the Department of State Visa Bulletin for October 2018.
For Employment-Based Preference Filings:
You must use the Final Action Dates chart in the Department of State Visa Bulletin for October 2018.
October 2018
UPDATE
USCIS have fixed the error. The main page now reads:
Current Month’s Adjustment of Status Filing Charts
For Family-Sponsored Filings:
You must use the Dates for Filing chart in the Department of State Visa Bulletin for October 2018.
For Employment-Based Preference Filings:
You must use the Dates for Filing chart in the Department of State Visa Bulletin for October 2018.
October 2018