Answer:
Explanation:
I think this is a very essential question to ask. While a lot of people want shortcuts to get things done(i used to too, when I was a student), shortcuts doesn't always cut it short. The reason is just as simple as that of any other subject that deals with theory.
Learning the limit definition gives ample knowledge about how the whole derivation works in general. Yes, quite alright, you can get the basic differentiation done when you don't learn that, but as someone who has gone far in calculus, I'd tell you for free, a time will come during computation where you'd get stuck because you never had that prior knowledge of definition.
Further along the line in calculus, you would be doing derivatives where you'd have to apply your knowledge of the definition of limit, and how would you be able get that done if you hadn't already learnt it?
Exactly!