There will be unfortunate tradeoffs to almost any strict limit we impose on not-yet-trusted users. Done well, user limits can be a minor nuisance, akin to this forum’s restriction on posting more than three links in a post. (New users often chafe against that restriction, but it’s for a good cause.) The key is to design limits that well-meaning newbies can intuit and sympathize with, and offer recourse to those who feel unfairly hamstrung by these limits due to their unique circumstances.
In various recent threads about vandalism, I’ve been careful to advocate only for technical measures that operators can configure on the fly in response to current threats. Although general tools are more difficult to picture and probably more difficult to implement, I think it does more good than to brainstorm specific heuristics and their false positives and negatives on this forum. These vandals are likely sophisticated enough to know how to find this thread, not to mention any copycats who come along in the future.