Hi Jack,
Thanks for your feedback. We actually used to have a more liberal threshold, but we ratcheted it down to 5 tries after an epidemic of attempted hacks on forum accounts.
We used to have a big problem with spam here, and the last thing I want is legitimate accounts being hijacked to post it.
If you find yourself close to the 5-attempt threshold, it's probably a good idea to use the 'forgot password' functionality or (if you're having problems with your password manager) disable it before trying to log in.