Every abstraction adds some complexity. So maybe the PoC skips all abstractions. Then we need to add a variant to something. Well, a single if/else is simpler than an abstract base class with two concrete implementations. Adding the 3rd as another if clause is simpler than refactoring all of them to an ABC structure. And so on.
“Simple” is relative. Investing in a little complexity now can save your ass later. Weighing this decision takes skill and experience
Like I used 100 gallons of petrol this month and 10 kilos of rabbit feed!