Not sure why people think the number of RMT tells is very light. No. They do spam a lot. Just make a fresh character and play around a bit on these RMT heavy servers. You'll see and understand the complaints. Blacklisting them doesn't solve the issue when they can just MAKE A NEW CHARACTER and start the process over. It's a problem, but just because it isn't yours doesn't mean it can just be dismissed entirely.

That aside, the best way to solve this is IP Addresses bans, Character restrictions or 'Story Completion'(Level) up to X point. This would at least slow down the spam process. I personally wouldn't be bothered if I didn't get them within every 1-5 minutes in multiples.