I respectfully disagree with that statement. In my opinion, caddies should be eligible for the HOF. The HOF should be about the individuals' contribution to the game as a whole. Whether you were a touring pro or not, if your contribution to the game merits recognition, then you should be in the HOF.
For example, someone like Butch Harmon who has coached many of the greats, could potentially be in the HOF. The same could be said for some of the great course architects, or PGA members and professionals, who have nurtured and grown the game outside of the spotlight of TV. In that same vein, caddies like Stevie or Squeaky, should also be considered.
I'm not saying they should be "in", merely measured for their contribution to the game. If they were elected to the HOF, I would have no problem with it.
Just my 2 cents. Feel free to ignore me if you think my opinion is nuts.