Tallifer
Hero
I disagree completely. Subclasses (and hybrid classes) are an inelegant way to handle multiclassing because each combination of classes requires a different rules entity, inflating the necessary amount of rules multiplicatively. You said it yourself: to get an uncovered combination, you have to homebrew. It eats up page count or creative time and energy to create each new combination. That is the opposite of leaving design space open. That is a system which makes you reinvent the wheel 12 x 11 times. (More, once you start adding new classes to the game.) A single set of rules which lets you immediately create any class combination is vastly more elegant. If one of my players wants to be a bard/monk, I don't have to do a thing.
Forsooth. 4E (which overall I enjoyed) had very restrictive and weak multiclassing rules. Therefore in order to create a greater variety of characters, the designers resorted to pumping out a multitude of classes... which still could not satisfy every niche. 5E's more generous multiclassing allows great variety without a needless stream of Players Handbooks 2, 3 etc to create new classes.