I agree with the weaknesses you've noted. If a bot service is determined to bypass the rules, some will find ways as long as the economy creates the incentive. But I think that if there is a line in the sand, some current bot users will respect it.

However, I do want to challenge you on your closing concept here though:

The focus should be on how to make sure that no account can drain significantly more than they spend.

First of all, this is not how economies work anywhere. Splinterlands has a fairly complex economy and there are many different ways to participate. In real economies, people tend to specialize in offering services in some area (ie employment) and consuming in other areas. Then supply and demand should help balance out the supply of various inputs - labour/time, skill, capital, innovation, etc. All of these have some value in an economy and allowing people to participate in the ways that they can add some efficiency makes sense.

But if we create the scenario that "NO ONE" is able to get more out than they put in, then the entire project literally becomes a money pit, not an economy. There is no return on time, skill or efforts. Which maybe is fine if we just want a fun game, but then we might as well eliminate the reward pool, let asset prices adjust downwards, and make fun more affordable for everyone.