The vast majority of my domains are still at GoDaddy. As an actual registrar, they are not that great.
But, they are popular.
Most of my sales are one-off sales to end users.
Pretty much everyone has a GoDaddy account or at least has heard of them. From my experience, it adds less friction to a deal.
Another reason for consolidation is if something happens to me, I don't want to leave a mess using a bunch of different registrars.
Dynadot is probably my favorite registrar though. They are just solid all around.
Brad