Because I find calling hugely uncomfortable if I don't know what to expect. If the person on the other side wants something from me, they can inform me beforehand via a message so I can prepare. An unexpected call interrupts whatever I'm doing and therefore has no respect for my day. If I take the call I'll have to refocus on whatever I was doing again which can take time and will take me energy.

Look, maybe it's because of Autism or AD(H)D, but task switching is something that costs me a lot of energy and causes a lot of chaos. When I get a message, I can easily decide whether it's actually worth my time, and in the case that it is urgent enough I can still usually clean up whatever I'm doing in such a way that I can easily continue. Getting a call forces my brain to drop everything on the spot (leaving behind a mess) in order to focus on the "being social " part, locks down one of my hands to hold my phone, and does not allow me to filter. Combine that with the numerous bullshit calls that I get from companies, spammers, and recruiters and you'll hopefully understand why I absolutely hate unexpected calls from random phone numbers.

Calls can be very useful, but I'm only okay with it when it's expected or necessary. Having a friend or family member call (or better: asking if we can call) because they need to tell me something important or need my urgent attention is the best way to do it. I don't want a message if someone needs me right now, because I could easily read the message only 20 minutes later. Likewise, we're obviously not going to have remote meetings via chat at work, not am I going to game with friends over text chat. But even then it's often not oldschool calls with their horrible quality, need to hold the phone, and lack of video or screen sharing. It's services like mumble or other VoIP services.