Captain Anorak's Guide to Gaming
Captain Anorak's Third Rule for Game Mechanics:
The more rules a game has, the more bad rules it will contain

All rules must work properly. The more rules you put into a game, the greater the chance that there will be some rules that don't work properly, and that a number of rules will interact in an unforeseen way to produce an undesirable effect.

Some games, like GURPS, try to have rules for everything. When a game has so many rules, the chances are that some of them will cause bad effects.

There are several glaring examples in GURPS of rules that have been badly thought out: a character with high Intelligence putting the minimum number of points into a language skill gains a speaking ability greater than that of an average native speaker; you can take a disadvantage (giving you character points back) which can be used to give your character advantages, like Gigantism (which gives you bonuses in some situations) or Dependent (which can be used to create a character with useful skills to help you); you can take the Delusion disadvantage for a large number of points, even when it would practically be of no disadvantage, or even advantageous (such as believing that the earth is flat in a society where not to believe so is heresy).