So
When I first read the 5e PHB, I was initially surprised that multiclassing was optional. However, when I saw the flexibility that backgrounds brought to the game, and the number of "pseudo multiclass " options (like the arcane trickster), it seemed that multiclassing wasn't really needed anymore.
The inclination to not allow multiclassing increased when I started seeing things like the sorlock or sorcadin. These seemed op and in some cases quite cheesy.
But lately I am starting to think that these multiclass creations are not as powerful as they might appear. A number of them need several levels before they "come online" . Meanwhile, single class PCs get a big bump at level 5. By the time the multiclass PC reaches that, the others have gained useful abilities like the paladin 's aura, or higher level spells, as well as being ahead ASI/feat wise.
By the time the multiclass PC catches up on those, the others now have the level 11 bump... and not too long after that most campaigns will end!
So while a white room analysis tells us that these creations are really potent, I wonder if that is the case in actual play...