A typical research paper is written at a very high level; often steps in the argument will assume the reader is also a skilled mathematician, and invite them to fill in the lower-level details themselves. This reasoning is as much intuitive as it is formal; I suspect it will be a while before proof assistants are as intelligent as the typical reader of a mathematics paper.
I think there's an outside perspective that if math isn't 100% logically verified, it's worthless, which doesn't really match up with my own experience. Most results rely more on the intuition of the authors than on the precise logic they write down; thus the surprising result that papers with logical gaps are, very often, still correct.