As written this article is terrible.
Classes as a mix of the attribute of the primary four classes is fine, to a point.
A ranger is more skilled in a skill system-ish way than a fighter and more 'hulk smash' than a rogue. But his also has a different skill set than a rogue with only some overlap in the stealth/perception area.
Which gets back to where I'm going: It is not enough for a 'secondary' class to mix attributes of the primary 4. They must have their own unique identities and abilities.
A Druid is NOT and has never been a less casty-more skilled cleric. He worships a different set of deities, draws from a different cultural milleau, and has always had his own unique powers. In AD&D through 2nd and 3e he has his own spell list, weapons and wild shaping. In 4e he had the primal power source instead of the clerics divine power source (Not sure I have that right, don't have books by me.)
Trying to cram Druids into a cleric/rogue hybrid without their own distinct identity would be an appalling lapse in judgement on the part of the designers.
Why on earth would they be willing to split the cleric up into multiple classes and then deny the Druid his own identity? The Druids powers were iconic and distinct for 3 editions of the game! (I'm not really clear on what happened to druids in 4e, so I can't speak to their identity in that system.)
While I'm not a huge fan of 4e, power sources are a useful design tool even if only as fluff, instead of mechanically. And fluff matters.
The iconic 4 are not the only base classes. If I had to identify primary classes (in the color sense of not being sub-dividable) I would say it is Fighter, Cleric, Wizard, Rogue, Druid, Monk, possibly psionisict.
From there you can mix and match. Maybe ranger
is a mix of rogue and fighter with just a dash of druid. Likewise a Paladin class based off of a mix of fighter and cleric attributes/powers is fine as long as he has his own schtick. And that's the key. I think every class needs at least one thing that they do that nobody else gets. Ever. Especially including the primary classes.
And this does not means feats that say fighter only, or swords that only work for paladins. I mean if the Paladin gets Holy Smite the nobody else does. If the Fighter gets "Hack them down" then nobody else gets it.
These abilities need not be there at first level, indeed maybe they should not be. Perhaps there really is nothing a 1st level fighter can do that Joe the Plumber cannot, if he gets lucky. But by 3rd or 4th level those iconic abilities should unlock and the heros move beyond the abilities of anyone without their fierce dedication to their chosen path.