In general writing, you have to be careful to balance repetition. At one extreme is what's been called "elegant variation"[0] and at the other is monotonous repetition, which hurts readability.

But, as you say, in technical writing, it's enormously irritating. I do a fair bit of freelance writing, and it pisses me off no end when editors and clients change a technical term for an apparent near synonym because they don't understand the nuance. It makes the sentence nonsensical and makes me look as though I don't know what I'm talking about.

[0]: https://en.wikipedia.org/wiki/Elegant_variation