I take this thread as tongue in cheek, but I will just add one last comment then I'm done with it.
To say that there is no way a high handicapper could hit a 300 yard drive in play would be wrong but it is so very, very rare. So rare that in 38 years of playing as a single paired with others and in countless tournaments I've never seen it. I say it's possible only because the odds are the big strong young high handicapper that swings hard statistically can't hit them all O.B. or three fairways over. Eventually once a week, once a month or once a year they catch one really solid and on the correct swing path,,,,eventually.
Probably the closest I've come to seeing it was a couple years ago they added a single to our group on the first tee. He was a Navy kid in decent shape and in his early twenties with a mediocre swing of the 20+ handicap range. I hit a solid tee shot in the fairway my normal 275-280 yards out. The Navy kid steps up and hammers a beautiful drive down the left side of the fairway 10 yards ahead of me at around the 290 mark. I though it was cool because it is very rare that I get out driven unless I'm playing with other scratch players or D1/D2 college golfers in competitions.
Unfortunately for the Navy kid that was the only good contact he would make all day long. The rest of the day his tee shots were in the 240 yard range with very poor contact.
The other problem that has also been very well documented across these boards and others is the simple fact that people do a bad job of guesstimating driving distance without some kind of valid measuring tool.
Another story from some co-workers a couple years ago shows how bad some people guess yardage. My co-workers(all of them high handicappers) told me that one of our fellow employees Mitch had been just hammering the ball 300 yards all season long in the company league night. I don't play in the league so had not had the opportunity to witness these gargantuan drives. So we set up a golf day where Mitch and I went out to play with a couple other co-workers. Well poor Mitch said he had an "Off Day" that round. He was never better than 25 yards behind me the entire round so at best he was bombing it out there a whopping 250 yards on a good one.
So basically it's a hard sell for a high handicap player to claim they can easily hit it 300 yards. Especially to those of us that have played this game for many decades and have reached a single digit to scratch level of play. A high handicap claiming they can consistently hit the ball 300 yards(at or around sea level) just doesn't match up to the reality of what actually happens day in and day out on every golf course across the world. I don't refute that there may be "outliers" from a statistical point of view that may be able to do it, but statistically there are too many high handicappers on the internet claiming they can for them to all be valid!
In the end it's a combination of ego and poor measuring or guesstimating of distance that lead people to believe they hit it farther than reality.