the dreams of distinction and glory that Gryffindors hold.
I think you've confused Gryffindor with Slytherin there.
I think this is a trait that Gryffindors and Slytherins share. Only that Gryffindors want "brave deeds to their names" and Slytherins (namely Phineas Black) feel that Gryffindors engage in "pointless heroics", and Slytherins want to be admired and feared in order to wield power. They do not care about being heroic and chivalrous on the way.
Again, people are not just one thing or the other. So yes, someone can be both brave and also glory seeking, and could do well in either Slytherin or Gryffindor. Snape and Harry could easily have swapped Houses, except for differences in personal values at 11 years old. Harry's father could have been a Slytherin, too. Dumbledore, too.
However, it's also possible to have just one of the traits, so a Gryffindor can have limited ambition (Neville, most of the Weasley clan), and a Slytherin can lack courage (Lucius and Draco Malfoy).
Also, not all Slytherins want to be feared in order to gain power/fame, so that's another unfair characterization. Slughorn, for example, found a way to acquire notoriety through the courting of promising youths, and gaining their friendship.
It's when a Gryffindor and a Slytherin have much in common that the real problems start, because then they both have ambition and courage, but are often pursuing opposing ends. So no wonder Phineas Black would curse the Gryffindors for their "pointless heroics," because said heroics are standing in the way of his own ambitions.
