And they're expensive. You pay thrice:

1. Engineering the generalized solution, then

2. Carrying the cognitive burden of this new indirection layer, and finally

3. Ripping out this premature -- and so likely wrong -- abstraction

Premature abstractions are like alcohol: fun borrowed from the future, and paid back later with interest. If unavoidable, choose the abstraction most narrowly scoped to your actual code base, not a future one. Humans suck at prediction. Ask me how I know.