Please don't auto increment the site_post_id value when the post is updated

Why site_post_id value is auto incremented every time when I edit a post?

For example, if I want to modify a specific site post via my own plugin, I have to use
"WHERE blog_id = $blog_id AND post_id = $post_id instead of referencing the site post directly like "WHERE site_post_id = 'unique site_post_id that isn't auto incremented on every post update'"