From the point of view of customer-facing jobs: in my more limited experience, the suitability of the job revolves around who's in control of the interactions.
In an installation type of job, the installer is in charge; they explain to the customer what is happening and what the customer should do next, and the customer generally listens, posing only questions relevant to the ongoing installation. It is also usually a single, linear task. This is fine.
In IT support, meanwhile, the customer comes to you with a request (or requests) which is often incompletely or ambiguously described. There may be more than one request, and more than one customer asking at once, and those customers may all consider their own requests urgent or priority. So: (1) every interaction is putting you on the spot; (2) you are expected to multitask; (3) you are expected to prioritise tasks in direct conflict with the customers' expectations of priority. Speaking as an autistic person, it's a recipe for complete meltdown.