This looks simple on paper, but in real client projects it often gets more complicated. If every client keeps the domain in their own registrar account, ownership is clean, but DNS changes, renewals, email records, and urgent fixes can become slower. If the reseller keeps all client domains in one account, support is faster, but handover can become messy when the client leaves. For those managing many client domains, how do you usually handle this in practice?
I'm speaking purely as a consumer. I'd rather have a trusted service handle everything than try to figure all that shit out on my own. It has to be a reliable, trusted service with excellent customer support. Over the past 20 years I've bought many domains and dealing one-on-one with sellers has always been difficult and stressful.