Partial explanation: we interpret these scales as going from worst possible to best possible, and

• games that get as far as being on sale and getting reviews are usually at least pretty good because otherwise there'd be no point selling them and no point reviewing them
• people entering competitions are usually at least pretty good because otherwise they wouldn't be there
• a typical day is actually quite a bit closer to best possible than worst possible, because there are so many at-least-kinda-plausible ways for it to go badly

One reason why this is only a partial explanation is that "possible" obviously really means something like "at least semi-plausible" and what's at least semi-plausible depends on context and whim. But, e.g., suppose we take it to mean something like: take past history, discard outliers at both ends, and expand the range slightly. Then I bet what you find is that

• most games that go on sale and attract enough attention to get reviewed are broadly of comparable quality
  • but a non-negligible fraction are quite a lot worse because of some serious failing in design or management or something
• most performances in competitions at a given level are broadly of comparable quality
  • but a non-negligible fraction are quite a lot worse because the competitor made a mistake of some kind
• most of a given person's days are roughly equally satisfactory
  • but a non-negligible fraction are quite a lot worse because of illness, work stress, argument with a family member, etc.

so that in order for a scale to be able to cover (say) 99% of cases it needs to extend quite a bit further downward than upward relative to the median case.