I don't develop Q2A, but I can basically say for certain this is something that would have been considered in the design of the post limit system. The developer/s would have gone ahead with it anyway, for a few reasons:
- The implementation is simple by comparison and uses less memory than a 'dynamic' solution.
- In general, it is unlikely a user would make use of this workaround on accident, which means the results aren't any worse in the majority of cases.
- Even if this system is targeted and abused by spammers (or somebody else), it eventually does what you want -- they'll hit a limit and have to wait.
- If post rate limits are the frontline of your defence against spam, then you've already got a problem.
I'll also add that in my experience, PokeBase has never been hit with high-volume spam (or anything that appears automated), and the majority of spammers seem to disappear after making one post (maybe after reading 'your post will be checked and approved'). So in practice, changing the post limit would only affect the very small number of real users who post so often they hit the hourly limit -- not a big concern.