For example my MIL is a medical doctor, so is obviously educated, speaks English well and uses a smart phone but wouldn't be able to send email to a new contact. Same with WhatsApp, she can reply to messages from us but I don't think she knows how to add a new contact to her phone.
That sounds like something my mother would ask me if (and previously when) she didn’t know how to email someone. Although it’d definitely lower the “conversion” rate regardless given the varying smartphone/PC ownership combined with internet penetration rates.
Speaking from experience as we once tried to help her to connect to a open WiFi which needed an OTP-based login via the phone and gave up after about 15 frustrating minutes for all three of us!
I've noticed working in design that people generally underestimate the average human's ability to solve problems, even if they aren't technically literate. But any increase in the effort department would reduce the amount of returns no doubt.