The proof of work is merely an iterative process which should increase individually for each user based on ripple address, ip, etc. to automatically normalize network utilization conditions based on an analytical process which basically says: HEY YOU, work this many times harder if you want us to listen to you because you been yappin too much lately. It's like when you enter your password too many times incorrectly, now wait 5 minutes or fill out this captcha.
This doesn't work as well. I'm not lying to you. We really worked hard on this problem and implemented the best solution we could come up with.
First, IP addresses are useless. You can only prove your IP address to someone you cannot to directly. Expecting clients to connect directly to every validator so they can see their IP address doesn't scale. You could have a central authority to which you connected and received proof of your IP address, but we're committed to having no central authorities. A malicious node could simply claim it got transactions from many different IP addresses and thus little proof of work is needed. If you make the node do proof of work to get other people's transactions in, this becomes an attack vector.
Account address only works if accounts are scarce, which gets you back to the same problem of how to keep accounts scarce.
CAPTCHAs don't work because you need a central authority. How do you prove to a machine that you solved a CAPTCHA for another machine not under common administration?
Today, anyone invested in a large amount of xrp(like you guys) could attack the network, and so effectively your solution is no different than an attacker investing in computing power.
No, because someone who did that would wind up divesting themselves of their ability to attack the network. In a PoW scheme, an attacker doesn't lose anything by continuing to attack. Also, in the XRP scheme an attack is only possible by a stake holder and only in proportion to their stake. In a PoW scheme, attacks are equally possible to non-stake-holders, those most incentivized to launch them.
All you can do with XRP is overload the network and deny service. To do it, you have to keep putting more XRP behind each transaction than those you're trying to keep out are willing to put in their one single important transaction.