Let's talk about ableism. This topic is important to RustFest, as caring about people with disabilities and mental health issues is one of the points where RustFest is ahead of the curve from other conferences. Even if you might not feel like you are being inappropriate, there are a lot of speech patterns that use disability-related terms and language in a negative way.
Given that we openly care about these people by putting our Accessibility Statement out, we also (willfully) open ourselves to that critique. That extends to you, as you are the most public-facing part of the conference.
There are words and speech patterns in everyday language that are harmful to people without the speaker necessarily intending or even noticing it. Words like "lame", "crazy", "stupid", "insane", "idiot" or "crippled" refer to human mental, cognitive or physical capabilities in a negative, demeaning way. These words are often used in a metaphorical way. People use them to state their attitude towards certain things they don't like or don't agree with. If you don't see "crazy" as an issue, try to put yourselves in the position of a person that is literally insulted as "crazy" because of a condition they have and then hearing you talk.
There are good lists for replacement terms and places to read up on this article. Also, you might want to check Wikipedia for a comprehensive list of disability related terms with negative connotations, in especially if you are not a native English speaker and might not be aware that that commonplace phrase could be problematic.
Luckily, these words can all be avoided by finding clearer formulations for what you want to express: That programming language, framework, tool, algorithm or thing is not "crazy". It might be difficult to comprehend, inconsistent, wonky, or seem nonsensical at first glance, and it's okay to state that. There are imperfect things. But it is also possible to see where they stem from, and the decisions of the people who made them follow a reasoning that can be described (even if one does not agree with them).
On the other hand, try to avoid ability/health-related terms like "healthy", "normal", "sane", "intelligent", "genius" or similar to describe things you endorse. Better say "that made sense to me", "the most elegant solution to our problem" or simply state why this is a good thing.
In fact, to experienced listeners, the use of ableist phrases is a telling sign that speakers have not found a good explanation on why something is not to their liking, and just put off the whole thing by putting in a phrase they had at hand. Mind that they also insulted many people in the process, both the persons that came up with the thing they are dismissing and the people that are commonly insulted using that language.
We feel that ableist speech has been getting very little attention compared to other forms of discriminatory language, and we need to catch up on that.