How cute. Sometimes you don't appear on credits. I have been working with more than 100 people on 2.9 millions of real-time safety critical code for nearly a decade. It has been unknowingly used by millions of people around the world and there will never be any recognition for any of us. Grow up.
In a few industries, for industry-specific reasons, who appears on credits and the exact contents of those credits actually does matter for career advancement purposes. Video games are one of those industries. Film and academia are two others. It is critically important to your future if you're an assistant professor or software developer working on the 3-D engine that your work get recorded in the industry-standard…
Now, if there had been some kind of official record then credits might have had a bigger weight but, with a lot of people's experience being in unfinished/cancelled projects, still it would not reach the level of critical importance IMHO.