Sure, that is why the game tells you how to allocate your ability scores based on your class selection. It's possible to create a wizard with an intelligence of 8, but only if you do the exact opposite of what the game tells you.
Then a solution for avoid players making unworkable multiclass characters can also be to simply include recommendations. Playing a Fighter? Recommend rogue. Playing a Paladin? Recommend Sorcerer. Playing a Druid? Recommend nothing. This isn't terribly hard to deal with.
