Today is the day of seeing -phobia used for hate and discrimination, isn't it.
- it takes responsibility from the ppl doing the shitty thing (yes, _especially_ if you're going to argue "it's not referencing mental illness, it's like in 'hydrophobic'!" - oppression is not a force of nature) and misrepresents the mechanisms
- it's awkward to throw people with phobias in with all that
- it is often used to score easy points from more openly ableist beliefs, see "homophobia can be cured" etc.
But if you don't actually mean to insult by drawing on ableist concepts and it's just the first word that came to your mind, then trying to find alternatives is a great process to start.
And these few examples were all from the realm of neurodivergency, I didn't include examples of when physical disabilities are used as metaphors for bad things. Which is also very, very often, and not doing that needs to be one part of that very same process.