However, to my eyes, and probably most people, 20230822090811 does not look like a "date string", it's a number. It's correct to display it as scientific notation if it's too many digits to fit into the width of a cell. Please let's not encourage them to interpret more things as dates and randomly break people's workflows.

Excel should preserve all the digits you enter in the cell even if it doesn't display them, though. That has nothing to do with dates. It's a problem with things like product numbers or keys that can end up with many digits.