I seem to be seeing a pattern here. You seem to be comparing a
completely low stat
character to an 18/18/18 character. In this case the high stat
character is going to have
an advantage due to natural ability. If the stats are the same but
have been placed in other
attributes, then the player is making a tradeoff, and should play up
the new advantages
that they have gained. If you decide to put that 18 into your
Intelligence instead of Strength
then they 1) get to pick more proficiencies from the Int bonus, 2)
might know of a monster's
weaknesses or imunities 3) deduce that there is a bolthole out of the
castle dungeons rather
than having to take the (heavily defended) main gate.
The other psyc stats Wisdom and Charisma also have benefits of high
skills. In head to head
combat (all other things being equal), the character with the higher
stats will generally win
(luck permitting). But head to head combat is not the be all and end
all of a campaign.

Sadly, high strength does not rule out high dexterity. So what you
get is
that player who wants to an play average-built but highly skilled
swordsmen takes high Dex and high Con, but the player who wants to
play
the wanna-be half-ogre, takes those as well, in addition to a high
Str.
And that's the problem...

- the Falcon