If you really do know something about theory, you should at least have a minimal knowledge of standard notation. Although you might not find death metal songs written in notation, you will find a lot of other stuff which is really useful.
I suspect that you are really trolling trying to get a rise out of people on this, but just in case you are genuine, if you continue to play music (on bass or in any other context), you will change your opinion on this rather quickly.
Believe it or not, if you work at the instrument long enough, you will reach a point where challenging "technicality" is not an issue - you will be able to physically play practically anything, but the challenge then becomes what to play and that is where a broad range of influences come in.
If you keep playing long enough, you will learn to appreciate playing at any tempo.
No, this forum is not hostile to metal at all. You asked for advice and the resounding message to you is that to be a better bassist, you need to broaden your musical horizons. That isn't anti-metal, but it is exactly what you asked for. Now, you can either take that advice you asked for (and which some other experienced musicians have generously offered) or you can igore it - that is up to you.
I suspect that you are really trolling and seeking to wind people up. If so, I hope you had fun. If not, I suggest you take the advice you have received in the spirit it is given.