Funny, because if you type "steam migraine epilepsy" into Google, there's at least half a dozen separate discussions in the first page of results when I try it. Multiple reports of the client affecting users with either or both conditions, and a significant number of examples where specific known triggers have been identified as being added into the Steam client at the time of the update (which, again, was 5 years ago at this point).
Also, if you've actually had any measure of experience with getting professional help with your condition, you've almost certainly heard that, like most issues which are directly connected with the behaviour of the brain, every case is unique and the response to different triggers will be different from others with the same condition as you. It happens with migraines, epilepsy, mental health conditions, and various other things involving the brain. It's great that you don't personally have to deal with the problems which have forced other gamers to leave the platform, but your personal experience will never change how someone else's condition responds to the same stimuli.