You really got discord all mixed up. Discord is not a part of steem. It's a larger platform on its own created mostly for gamers to congregate and chat while they play and discuss about other things in general.

It is an instant messaging platform which means that it serves a purpose that steemit doesn't, i.e chatting instantaneously and more smoothly instead of going back and forth on a comment thread, which you'd agree isn't so effective. And that is why most early steemians flocked there after the breakdown of steem.chat.

Plus it has a server format which is great for community building.

Anyway as for the four digit tag, it is merely to differentiate between users of similar usernames, because unlike most platform there's no "sorry, username taken" on discord. You can use any username you like but there'll be a unique code attached to it to differentiate you from others with that same username; think of it as a cryptographic public key which most cryptocurencies employ for security.

And the code isn't even compulsory to add people as friends. Most people meet on discord by belonging to mutual servers where you can just dm someone without knowing his/her username or code tag.

How about you join this server then if you're not comfortable with the tag? I can message you directly from there.

All I ask is that you give discord and maybe steem one last chance LOL.

Here's the server link again: https://discord.gg/UX6PatD . Cheers