I too had no trouble getting characters from level 1 to level 2 in a 4 hour session.
Probably something to do with the number of encounters I find it to be normal to experience in a 4 hour session, and how I don't have any illusion that I am meant to assess role-playing encounter difficulty on the same risks as combat encounters, but rather on simply how difficult the primary desired result of the role-playing is for the players to get (i.e. a role-playing encounter is not "deadly" because characters might actually die if the role-playing doesn't go their way, but because getting what they prefer out of the encounter is roughly the same chance of success as defeating a deadly encounter without anyone dying.)
Also, your wonderings regarding that one of the designers doesn't even use the system are slightly misplaced. The design intent of the encounter building xp budget guidelines is not that every DM use them; only that those DMs who want a guideline besides their own whims have one available that functions well enough that if followed is not likely to result in undesired outcomes (such as an encounter that says it is "easy" being deadly in practice).