This is the single most important trick for factoring out shitty code. I cannot believe how many times reification collapsed complexity in our code base, or how not using it was the source of bugs.
If you have cascading ifs, there is a good chance there is a huge set of ifs for every place this type system is missing. Meaning, if you wanted to add another "case" to a feature, you are modifying cascading ifs in 5-10 places, not even just one.
Wrapping up all of this code into an implementation of an interface, that is "hooked in" at each contact point allows you to add a cohesive new use case by generating a new implementation of an interface, instead of "forgetting 2 places in the code" and causing massive bugs or issues because of it.
If you have cascading ifs, there is a good chance there is a huge set of ifs for every place this type system is missing. Meaning, if you wanted to add another "case" to a feature, you are modifying cascading ifs in 5-10 places, not even just one.
Wrapping up all of this code into an implementation of an interface, that is "hooked in" at each contact point allows you to add a cohesive new use case by generating a new implementation of an interface, instead of "forgetting 2 places in the code" and causing massive bugs or issues because of it.
It of course, also makes it easier to test!