I'll continue to use alternate accounts until it's prevented, if it ever is.

I've complained about it many times before (even earlier in this thread). Too many times have I had some angry weirdo try sparring me from a brand new account, or even a negatively boosted account, for the sole purpose of trying to tank my score. So, rather than constantly complain about something that I'm not seeing being fixed, I've taken it into my own hands and I use them almost like insurance.

I gradually let my alts idle off the leaderboard anyway. The leaderboard is hardly even an accomplishment anymore. It is what you make of it. There is no reward or prize for it or anything.