I agree, in addition, spending funds instead of spamming free transactions could basically be a good indirect…

I agree, in addition, spending funds instead of spamming free transactions could basically be a good indirect proof of humanity solution (of course, weighted with some other factors as well). In many cases one of the fundamental functions of fees, beyond generating revenue for the maintainer, is to prevent the system from being spammed with unnecessary transactions. It's not unreasonable to appreciate the act of spending onchain.