HoMM3 HD is a mod (add-on) for the game Heroes of Might and Magic 3.

If they're already using a mod on the other side, there's no need to explain anything. If a person is using a mod, it means they're ready to use all its features.

Are you sure? People are still playing 2.94 quite comfortably and aren't too concerned about updating.

If a bug is very rare and has little impact on the game, then there's no harm in fixing it; no one will notice, and no one will be disadvantaged.

Try explaining that to someone who doesn't care whether it's a bug or not and who wants to play the way they're used to, but with added convenience. You've been playing with gems in the starting bank for many years; how many followers do you have?