I think you’re mainly speaking from a place of percieved opinion than tech knowledge but I would suggest for you that you only use a landline for phone service. Have you ever had a job working with various network services for random customers and speak to customers to answer questions?
From the context of your previous comments, it seemed like you were talking not about not having a mobile phone in general, but rather a SIMless phone. Using it over Wi-Fi only is indeed doable - but you’d need an Airplane Mode on an OS you can trust, just having no SIM would not be enough.
Also no, I did not have such a job - I don’t understand how this question relates to the conversation.