It would be less condescending if the author just stated what type of math was used and left out the passive aggressive nonsense about people "unwilling to lear

It would be less condescending if the author just stated what type of math was used and left out the passive aggressive nonsense about people "unwilling to learn difficult concepts through prolonged mental concentration and effort." And I think that's what the OP is questioning. Most technical writing will spell out what's expected from the reader, but articles about FP also tend to have a "... if you're smart enough" sentiment added in.