What are the disadvantages of using bootstrap with style redefinition at the sass level?

Question

css

It was inspired by the fact that each layout designer invents his own mini-framework, and when changing the layout designer, the new one will spend time getting acquainted. The framework solves this problem in part. But what are the downsides?
The options "a lot of extra stretches" is not accepted, everything superfluous is turned off through the collector.