That person explicitly dismissed "advanced mastery" and thus challenging and bettering oneself or themselves as being non-inclusive. I find this attitude highly offensive, because my motivation towards mastery is not of that kind. I'm happy to include people, explain them my code, help them along towards mastery.

Software also has an ongoing quality crisis, all while being more and more influential in people's lives. That person's attitude towards writing quality software helps to deepen that crisis and is therefore harmful.