On my website, I have one author that does not want to have a credit name for the articles that they publish. To accomplish this, I can add an additional column to the WordPress user database table that I can edit manually. This is more efficient than holding this in a separate database and querying that. I’ve tested and this is working.
However, I assume that in some cases a WordPress update may cause some schema changes to the database. Does this mean that the column I added to the table could be removed automatically by a WordPress update?
It is unlikely WP will remove a column it didn’t create. Also, I must ask, how many nanoseconds are you’re saving by skipping the joining of the posts table on the post meta table?
And a more viable solution would be to create a dummy user account and have this user select it as the author when publishing posts on your website.