I'll try and keep some relevance to BR, here goes:

There has been a lot of use of two phrases high and low stats, but
no clear definition, you rarely get all low scores or all high scores. I've
just started DMing a new campaign, Dark Sun to be precise so that
necessitated rolling new characters. Anyone that has played DS knows that
some pretty high scores are attainable.

But each one of the characters has one attribute below 10, I use the
attributes rolled to figure out a bit more about the character's background
and personality as well as his skills. The wizard in the party has a high
charisma 15, intelligence 18, and yet 9 wisdom. I got together with the
player and we decided that he should be a leader type, capable of creating
good plans but a little over confident, both in assuming his plan will work
and that people will follow him.

A high attribute can bring a lot of bonuses, but IMO it's better to
match it with a lower score in another to develop a personality. Why have a
13 that means nothing positive or negative, when you could have a character
with a strength of 7 for example. Rather than playing him as a weakling
looked down upon by others, he can turn this to his advantage, getting
stronger players to carry his equipment, face monsters for him and my
personal favorite open doors in dungeons. "tell you what, I'll hold your
lantern while you open the door.....oh that's gotta hurt!" :-)

Characters can have high stats but not necessarily the same
advantages, Avan and Boeruine both have excellent CHA scores but the way
this is expressed for each is varied. An NPC might react differently to
each, based on what he considers charismatic, the same should go for
players.

That fighter with 18+ strength is bound to be heavily muscled and a
large chap all round, this is what opponents see, whereas the fighter with
14 STR is above average but with his longsword mastery and fighting style he
could be a far deadlier fighter. If you think that players with high stats
should achieve more then make them do so. Penalise him for it, a powerful
fighter with high stats will draw the enemy's attention so make him fight
more opponents.

While they are occupied party members with lower scores can take
advantage, thief's backstab, Priests/Wizards spells etc. I view it as a
roleplaying challenge to play with one or two low scores in that you have to
think up better methods of doing things. But there is an equal challenge
with high scores in that the other characters expect more from you, there's
always another quest that you have to complete.

To put this all into a BR context, characters with excellent stats
might well attract an Awnshegh's attention, either as a potential rival or
as a nice snack.

Nick