Blockchain has been used previously (see dogetipbot) in a similar concept and worked well.
Since tips would be given at the discretion of users finding certain comments particularly good, a bot would only be able to abuse the system by creating good comments.
I have seen of many instances not being funded sufficiently through donations. If the level of user donations is able to cover only 50% of operation costs for an instance, if monthly upkeep is say $60, then it is reasonable for an owner to subsidize the rest. But, as lemmy (and consequently each community) grows in popularity, a 50% coverage of operational costs is simply not sustainable. That is, without a tactic such as Wikipedia's notorious pity-ware ad banners.
Providing an alternative method of funding could assist instance owners to keep the community running.
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