It depends on how big the difference is. A fighter with a 20 strength and con is going so shine compared to a fighter with 14s. Even then, there are some players that are just more effective while playing their characters than others.
Just FYI since this was the first post in the discussion where the PCs are identical except the STR difference:
For a d8 weapon, each 2-pt STR bump (+1 modifier) increases average damage by 0.5225 points or 12.3% over all d20 rolls.
For a 2d6 weapons, the same average damage of 0.5225 points, but just 9.3% over all d20 rolls.
Now, if we compare STR 20 (rolled+2) vs. STR 17* (15 standard array max+2), how does it look?
Well, for d8 weapons, it is 1.0445 points, which results in a 24.3% increase over all d20 rolls.
For 2d6 weapons, it is also 1.0445 points, but this results in a 18.5% increase over all d20 rolls.
(*I don't know if you can start with an 18 without rolling in 2024...)
How noticable is basically 1 point of extra damage on every attack? In my experience not much, but the percentages make it feel like there is more impact than there really is. If your fight lasts 3 rounds, how much does that 3 points really impact the fight when you consider how swingy both attack rolls and even damage rolls can be? Again, in my experience not much.
So, I don't think personally most players would notice any appreciable difference having say, a STR 16 vs. STR 20 when it comes to their effectiveness in combat.
(My calculations involved STR 14, 16, 18, and 20.)
