That is true. Spreadsheets work the exact opposite of Airtable, in that they start off with a full sheet of empty cells you can then fill in later. With Airtable, nothing exists until you create it.
Note that in Airtable, you would want to make the rows the dates and the columns the channels. And like you said, you would need to pre-generate the records. That could be a pain, but it would only be 365 records per year, and you’d only have to do it once per year.