It can be really hard to judge what level to aim for, and people who know a lot about a thing tend to way overestimate where the floor is. And if you overexplain then some of your audience dips because they think it's too basic of an essay, video or otherwise.

I still remember vividly HBomberguy being about to explain who James Rolfe is and then going 'wait, I don't need to explain that' and I was very annoyed.